Sum and Difference Trigonometric Identities
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- เผยแพร่เมื่อ 17 ก.ย. 2024
- Using the Sum and Difference Identities, I do examples of evaluating trigonometric expressions that require the use of the sum and difference identities for sine, cosine, and tangent.
At the end of the example of sin(195) (at 8:04) I say the denominator of the answer is 2 but 2*2 equals 4. Sorry for the error. There is an annotation correction, but you will not see it if you do not have Flash.
Check out www.ProfRobBob.com, there you will find my lessons organized by class/subject and then by topics within each class. Find free review test, useful notes and more at www.mathplane.com If you'd like to make a donation to support my efforts look for the "Tip the Teacher" button on my channel's homepage / profrobbob
I just watched a man fix chalk board light bulbs
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How'd it work out for you?
I'm in the exact same position as you now, minus the soldier part.
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I just want to thank you on behalf of every student in the world that is having problems in math. Your videos are by far good enough to make your viewers pay to watch them and I greatly appreciate that you keep your videos free. You can tell that you truly love your job and you are the reason myself and 1,000,000 other kids have better grades in math.
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I'm in college taking PreCalc and these videos are WAY more helpful than the lecture my professors provide, great work!
Thanks for taking the time to seek outside help and choosing this channel to study with!
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60% of the time it works every time.
But for real your videos have always helped with really understanding what it is I'm doing. Thanks a million!
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Sounds like a perfect time to share this free resource with your teacher too:D
im a sophomore in high school and my teacher is terrible at teaching. These vids really help me understand everything thats going on. thank you
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I have failed my last three trig tests because my college professor can't explain anything worth crap. She goes through 3 sections in one day and takes no questions. I have learned so much more watching this 15 minute video than I have in over 3 months of class. You will save my trig grade! :D THANK YOU SO MUCH!!!!!!!!!
The broken light, great comedic relief! Thank you so much for posting your teachings. I greatly appreciate them! Gives me a much better understanding of the subject. You make Trig easy and fun! ;) Can't get enough of your videos!
Nice video sir it really help me
I am from India🇮🇳
Thank you from Florida for watching Rajesh! Glad I could help.
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This was such a great video, very clearly explained, thank you! I love how you re-drew the bottom light bulb to look broken after you broke it.
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the answer in your 1st example is sqt. 2 - sqt. 6 over 4
+Dolf Glenard Resuello he corrected himself using annotations. Turn them on and see for yourself
+RedNuii thanks for the help by pointing that out!
that's what i was thinking!!!
yh it confused me heheh
Whew okay I’m glad someone mentioned that, I thought I forgot had to multiply fractions for a second 😅
You are absolutely amazing. I really do appreciate a teacher with so many charisma. And I see how you always write your viewers back. Anyone can clearly see that you have a passion for teaching others and it is one that I can really appreciate. Thank you for all your videos they're amazing!
THANKS for watching and noticing all the little details Linda Thai !
My wife helps a lot with comments and teaching is defiantly my passion...don't forget to like, subscribe and share to help these free educational channels groW and remain free:D
I have been mucking around with sin and cos drawing circles in computer programming for years without really knowing what I was doing, so this x and y based style makes much more sense to me than talking about opposite, adjacent and hypotenuse sides.
Glad I was able to wash away that muck ShamelessHorse ...gotta stay out of those stalls without boots on:)...lol
I'm giving my students a break and getting (forcing, suggesting:)) that they watch you. We all get a great kick out of them and they work great. After teaching the "easy" math for many years i now have the opportunity to teach a higher level and your videos have helped more than you can imagine. Thanks:)
THANKS Joe!!!
It's always nice to hear that a fellow teacher is sharing and supporting!
My wife and I have put alot of time and effort into the growth of this channel, mainly just trying to spread the word (since we've never seen a math video go viral:) and so everyone who wants to study has the opportunity to do it for free! Please share with fellow teachers and congrats on the new classes.
Seems I'm moving in reverse...I'll have 5 preps next year, including 2 classes that are not honors or AP...seems there are just not enough students to fill those classes:(
Your first problem, sin(195), resolves -0.5176380902050415246977976752481 on the calculator, however, your answer of (sqrt(2) - sqrt(6)) /2 resolves -0.5176380902050415246977976752481.
Your denominator should be 4 and your result would be the same as the calculator. I'm sure it was an unintended blunder.
I should tell you I am glad for your time and efforts. I encourage you to continue these lessons; many high school kids are appreciative.
Thank you again.
There is an annotation correction and I have a note about this in the video description. Sorry about that:)
i see this guys videos, make sense and ok they are easy. I take the test at school and I don't remember shit
xD that intro scared the heck outta me
get ready...there is much more to come!!!
ProfRobBob thank you by the way, it really helped out alot :D
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ProfRobBob i'd be happy to!
Cause u r a pussy nigga
My college pre calc teacher doesn't teach very well. These videos have helped me through trig SO MUCH. I can't thank you enough. Thank you :D
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I always come to you when I have no idea what I learned in trigonometry (which is all the time) and its really helpful!
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I'm studying for my final and this was a very quick and thorough explanation. Thanks for the video. You seem like an amazing teacher.
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I like the chalk board. It's very old-school.
THANKS..I too LOVE my chalkboards! And this one is from an old school built in 1926...I'm one of the only rooms at the school I teach that still has slate chalkboards in my room...the other ones have all been replaced with whiteboards:(...It's so sad
Thanks for watching too!
I'm new to your channel and for real, you make each topic so clear to me.
Coming from a C, I got my first A on a Chapter Exam because of your videos
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+Nicky Magallon must be your first video...lol
You'll get used to it after you like, subscribe and learn some more:)
+ProfRobBob pfffft she must be new
Yep, I did as well
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Great video and great channel. I will make sure to recommend you to others. I thought I wasn't going to survive in PreCalc 2 with my 75 year old teacher who is tough to understand. THANK YOU SO MUCH
I didn't just work on the top portion (numerator), I applied the sum identity for tangent to rewrite the expression. Thank you:)
I think it's hilarious that he said 'you dont wanna be drawing little triangles everywhere,' cause I totally do. Great presentation, really helped fill in the gaps of my textbook, thanks!
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this is the topic on our trig now... i really don't understand what our prof discussed. now I've realized that this lesson is fine :D thank you :))
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Congrats BAM Man, thanks for the videos. Like the directness and speed with which you get to the point. Thanks for the addition of the light bulbs and keep mixing it up. Best to you.
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Seven months and still watching and supporting...THANK YOU!
Man why cant all math teachers be like you? XD Mine for the past 2 years have been foreign and they talk fast and i feel like they're speaking another language. I was hoping i could seek help on youtube. Then i found Mr. Tarrou. You explain a lot in so little time. Its amazing! You are my go to math teacher now. :) Thank you.
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Well I'm glad to see that you decided to seek help on TH-cam or you never would have found my channel! I'm glad you find my teaching style so helpful and choosing me as your go-to teacher! I'm looking forward to having you as one of my TH-cam students. Just a thought...If others in your class are struggling too, maybe you could start a study group using my videos...it helps when you have others to bounce questions around with:)...and please share my channel with your friends too:D
This vid definitely helped me out a bit.. these kinds of problems are the ones my teacher gave at the start of class, except we had to do them in 2 minutes, not 14. And then she just pushed right forward to way more complex and ANNOYING expressions. Then she usually goes on to say "remember there's room in my non-honors precalc class for those of you taking this long." Like cmon. Anyways, thanks for the video, helped me keep up today.
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Wish I had you as a teacher! You've helped me a ton and your blackboard is awesome!
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I love my blackboards too, thanks again!
Thanks for your efforts. I will look up both colleges and send my letter to whatever they call their student/academic learning center. I appreciate the support!
Thanks...I'm working on just that right now. I will be teaching AP Calc next year and I'm currently working on that library. Thanks for supporting by subscribing and I look forward to another photo from that best dressed dog:)
We have a song that we sing to remember what to do in regard to sin and cos! Thank you so much for you videos. You are a savior.
I wish annotation corrections were not Flash so they would show up on iPads and computers without flash. I corrected this problem...because 2*2 does equal 4 and not 2!!! Thanks for the note. I am going to add the correction do the description of the video as well:).
Mr. Turoo, you're like, the guardian angel of math.
Thank you for the kind words...it's students like you that make me love my job! Speaking of that; I loved your "jump on it" video and commented that I need to do a cameo appearance the next time you do a high school production...you keep up the great job too!
Professor RobBob, thank you for a mammoth video/lecture on Sum and Difference Trigonometric Identities in old fashion everyday Trigonometry.
Such a very great man, you always help me on my math lessons. BIG THANKS!!
+Orlando Almandrez you're welcome...THANKS for taking the time to study!
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Thanks! My teacher rushes through this stuff so I don't understand it. Have a thumbs up from me.
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i already liked it
More than one comment and video watched....you are working hard aren't you?!...speaking as a teacher, great job on the extra effort and thanks for watching and supporting:)
It helps to love it when you're teaching it! Keep watching...maybe you will learn to at least enjoy it more:)
We teachers all have our own style...mine just happens to be a bit on the entertaining side. My mission in life is to "MAKE MATH FUN" while learning....keep watching and sharing my channel...thanks:))
This is absolutely brilliant! (This coming from a college student)
BAM!!! superemepwr
hahah brillliant!
My quick calculus included this in the review, just wanted some fast standard examples of them, Thank you bro.
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That's a true statement. But to get an exact answer we need to use angles that are on the unit circle and 15 degrees is not. Thanks for watching:)
i dont know what i would do without you 1000T*ThankYou
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Absolutely the best Math help on TH-cam!!!!! Thanks so much, Please Keep it up!!! :)
THANK YOU!...and thanks for choosing Tarrou's Chalk talk to watch and learn from!
Congrats Nick...dual enrollment is a bit harder but the rewards are much greater in the end! Just keep up those good study habits and you will do great! (after all, you have my videos to fall back on next year:)...lol
I'm watching your videos for advance studying and sir, you never failed to amaze me. Thankyou so much! Keep it up! BAM!!
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Aye sir!!! :D
Andrew Villaruel :)
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If Sin A = 5/13, your reference triangle could be set up with y=5 and r=13 giving you an x=12 with the pythagorean theorem. With Tan let y = -sqrt(3) and x = 1
So simple when hearing and seeing it being explained like this! Thank you so much! Glad to have come across your channnel
+Caitlin Bencsko
You are so welcome and thanks for studying and subbing and please tell all your friends, class and teachers to watch and do the same:D
That's the first time I've gotten that as a title...but my wife and I really like it! She says we should put that on a t-shirt:) Keep watching my videos...maybe you'll see it someday and say to yourself "I gave him that name"..thanks again for the nice comment.
Thanks for understanding and I hope you will continue to choose my channel or share it with others:D
you are the best teacher ever. thank you. my math teacher sucks. and your videos are actually very interesting and fun. thank you. so much. :)
You are a life saver. Hopefully I do well on my unit test coming up soon. Plus, you're really energetic and lively, and I kind of zone out on other monotonous TH-cam videos!
I too hope you pass that unit test like BAM!!! jessebun !
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You're Awesome Man... Really helping me with my online Maths course... I review everything with your videos to make sure I haven't missed anything :) Keep it up bro!
+Craig Farrell glad to hear that you are finding this channel so helpful and thanks for taking the time to share your learning experience with us! Thanks for liking and subbing too...please tell all your friends and classmates to watch and do the same to help this channel keep growing:D
I hope you are feeling better. Sorry I missed your comment. Thank you very much for the support again.
Just follow the signs of the identities and the values you get from the unit circle.
Thank you so much!! Your videos have saved my pre-calc grade!
You're welcome...let's say we saved it together...YOU took the time to find help on TH-cam and choose Tarrou's Chalk Talk to get it from...BAM!!!
Please SUBSCRIBE and share your experience with your friends and classmates and help my channel continue to groW phinckle5 !
Thank you:D I appreciate you watching.
This video was well done helped me out so much! We just started this part in class but did not get to go into detail before the weekend. I wanted to get a jump start on homework and this video brought it all together for me. Thank you for taking your time to make and post this video much appreciated!!!
You're welcome...and THANK YOU for taking the time to look for help, choose my channel to learn from, sub, and to thank the teacher !
this is amazing... you were able to help bring clarity to a subject that even my math tutor failed to teach me. thanks so much mr. tarrou!
You're welcome...I hope that earns me a like and a new subscriber too:)
...and while you're at it...please keep sharing so we keep growing:D
Thank you for watching:) I am thrilled I could help.
Thank you for saving my trig grade
Too much anticipation for the first 5 seconds waiting for you to jump in haha
LOL Isaiah Macadam ...that was one of my early videos and I had not perfected my "jump" yet:)
Thank you very much Mr. Torrou! I was preparing for my Pre calc final exam over the past week and referenced your videos a lot! Very useful!! Bam!!
Akshay Sambandham you're welcome!
Thanks for studying with my channel too, keep spreading the word :D
Just got results back from the county for my PreCalculus exam. Got the highest grade in my class! Thank you so much Mr. Torrou!
Akshay Sambandham BAM!!! You're welcome and thanks for studying!
Also, CONGRATULATIONS and I hope you told your teacher about my channel so they could share it with future students:D
Thank you so much!! It's people like you that help me get through high school!!!
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Thank You for spending the time to do all of your videos. It is helping me out so much.
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thank you for this video. thanks to you I'm really starting to understand what's going on.
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videos are veryyyy helpful and thank god you will be making Calc videos. I'll be in calc 1 at junior college next year when i'm only a junior in High School.. God help me..
Only if my teacher had your charisma, i feel like i'm falling behind and this video picked me back up and i'm ready to do more math! :D
BAM!!! Kyle Ludwig Thanks for the compliment and I hope my videos continue to keep you inspired and motivated to "do more math"...then when you have filled your brain full of math, you can share your learning experience and like, subscribe and share my channel with all your friends, classmates and teachers too:D
I did not just work cosine, I recognized the expression matched the right side of the difference identity of cosine...and then applied that identity
I am sorry, but right now I am just trying to stay ahead of my Geometry class...a new topic I am teaching this year along with 3 other subjects. I am also starting to plan for Calculus next year. I hope you find the proofs you need, but I cannot help right now.
I'm studying for the accuplacer test. This was helpful, thank you.
+Keith Roussel glad I could help:)
*me not wanting to go do my homework*
"BAM GO DO UR HOMEWORK"
*my willpower reviving itself after months of burnout ready to absolutely destroy some homework*
7:58 when you multiply fractions you multiply the denominators too so it should be over 4
Now that you know where to find me…you can just watch a video whenever you want to learn more math:)
Awesome videos Mr. Tarrou I have a question regarding the Tan 70 + tan 50 problem. Is there a reason why the bottom portion of the problem was not worked on ?
I did not work with the numerator or denominator, I noticed that the given problem matched the right side of the sum identity for tangent and applied the identity to rewrite the expression.
You are a PRO at erasing!!! Also great help. Thanks :)
just wanted to say you are awesome and this helped me alot
and i think its cool that you try and make math fun
ProfRobBob, I'm so thankful for all of your videos! They really help me understand the concepts! I told my trig class about your channel and website & hope they all check it out! *doing my homework!* :)
+Rose A that's AWESOME!!! You make this teacher proud:)
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I can't say thank you enough Pearson mathlab only helps so far.
knucklechukka Thank you for choosing my lessons to learn from!!! Are you taking an online class or just have the Pearson mathlab as a extra resource for your traditional class?
ProfRobBob Pearson is the program our classes homework is done (trig/coll alg) sometimes it has a tendency to be lacking in explanation on its steps
Do you mean the annotation I had to add? Because 2 times 2 is 4.
Yes, a video I can actually understand! Thanks for the help, now I can do my homework tonight!
Thanks for choosing, subscribing and taking the time to seek extra help to "do your homework"…words that make a teacher proud…BAM!!!
no problem. I found the proof on youtube. you have a great channel. keep up the good work.