Wow! Explained amazingly! I've always been taught in maths to just accept rules without understanding them. This is annoying as it helps to know what you are doing and why it is working! Thanks you!
I have the same problem. No matter how much I force myself to learn something, if I don’t see the practical use for them, my brain just goes. *wut dis, useless to life, sucks to be trig* but if I know what I’m actually going to use it to do, then my brain does insane. *wuts food, I only need trig to nourish my-*
It's more than just understanding them. Proofs are essential in showing that something is true. Lots of things that seem true may not be, but a proof "proves" it is.
It is really a sad state of affairs where in education, we are just meant to accept this is that, and apply it. Obviously, you get no understanding of the topic except for 'it just exists'. This video is amazing in this case.
Bro I think math teachers really undervalue explaining what might seem so simple to them, like sine rule was so damn confusing to me because as soon as it got to rearranging equations with fractions I just got entirely lost, but the simple act of explaining exactly what he was doing when he rearranged it was so useful.
Just one slight criticism for if anyone is using this as a template. When he drew the triangle to prove sine rule, he shouldn't have made it look like a right triangle, as students might think it has to be and so struggle to see the symmetrical result.
@6:28 you say the case for angle C is the same. But I tried to work that out and I cannot form a right triangle from either A Or B(using the same triangle). Because A & B are acute angles and it doesn't make a perpendicular line at 90° on the opposite side. Can anyone give me an insight?
lololol imagine doing maths in the holidays with no obligation other than, i wanna get 100% on the next test, and dam this teacher is just like mine!! and so helpful!!
Excuse me sir, would the ambiguous case in sine rule still apply if you're given a diagram? Say, you're given a diagram where the angle's clearly acute, but using the ambiguous case, the sine rule gives an obtuse angle solution as well (the angle sum of the triangle is still less than 180 degrees). In that case, do we just take the acute solution or both the obtuse and acute solution? Thank you
Providing the obtuse solution takes a few seconds and you shouldn't be marked down for it especially if the diagram does not indicate that it is to scale.
The law of sines still applies to obtuse triangles. The one problem that will happen with obtuse triangles, that wouldn't otherwise happen with acute triangles, is that if you depend on using inverse sine, you could get the wrong answer, even if you set up the law of sines correctly. The reason is that inverse sine assumes the answer is between -90 deg and + 90 deg, hence it will give you the acute answer by default. When the angle you are seeking is known to be obtuse because of other information in the problem, you'll have to "mirror image" your answer around 90 degrees. I.e. subtract it from 90 deg, and then add 90 deg. Because sin(90deg - theta) = sin(90deg + theta). An example is 60 degrees and 120 degrees, which both have the same sine.
“It checks out I’m done”
The maths teacher version of a mic drop
Wow! Explained amazingly! I've always been taught in maths to just accept rules without understanding them. This is annoying as it helps to know what you are doing and why it is working! Thanks you!
I have the same problem. No matter how much I force myself to learn something, if I don’t see the practical use for them, my brain just goes. *wut dis, useless to life, sucks to be trig* but if I know what I’m actually going to use it to do, then my brain does insane. *wuts food, I only need trig to nourish my-*
It's more than just understanding them. Proofs are essential in showing that something is true. Lots of things that seem true may not be, but a proof "proves" it is.
@@jonahansen yeah definitely (says a 4 years older version of myself...)
@@jgreen8339 Ha! That's nuthin'. I've gotten replies from comments I made to TH-cam videos 13 years ago. Yeah - I'm old now.... OK Boomer!
It is really a sad state of affairs where in education, we are just meant to accept this is that, and apply it. Obviously, you get no understanding of the topic except for 'it just exists'. This video is amazing in this case.
I wish my teacher was this good…
Thank you so much for the video! I really wanted to understand the process behind the final equation, and it's really well explained here.
Thank you so much, you've helped me understand it. Clear and very analytical!!!
thank you so much for your teaching videos! :D you really ensure that students understand the material.
Thank you Mr. Eddie Woo
I'm 30 and I can't believe I'm watching this for fun hahaha
You are 30 that's that's still early way to go. I am 47 and I am watching all his lectures 😀.
@@milindmore7093 well hes 32 now ur a bit late on the comment lol
@@iambehindyou9607 Oh! 😀 I am happy to see that gap has reduced.
Im 13 lol
Great video! Thank you so much Mr Woo :)
Awesome teaching sir, thanks :) I needed a reminder of all this haha
Bro I think math teachers really undervalue explaining what might seem so simple to them, like sine rule was so damn confusing to me because as soon as it got to rearranging equations with fractions I just got entirely lost, but the simple act of explaining exactly what he was doing when he rearranged it was so useful.
bro summed up whole 5 weeks in 20 minutes
your videos woo'd my mind 😂🙌
You explain so much better than my teacher
Just one slight criticism for if anyone is using this as a template. When he drew the triangle to prove sine rule, he shouldn't have made it look like a right triangle, as students might think it has to be and so struggle to see the symmetrical result.
@6:28 you say the case for angle C is the same. But I tried to work that out and I cannot form a right triangle from either A Or B(using the same triangle). Because A & B are acute angles and it doesn't make a perpendicular line at 90° on the opposite side. Can anyone give me an insight?
thanks man
Hello teacher from Cambodia
lololol imagine doing maths in the holidays with no obligation other than, i wanna get 100% on the next test,
and dam this teacher is just like mine!! and so helpful!!
"and now, before i sine off on this" .... cheeky
You should be a maths teacher mate, top stuff
shout out from philippines
Excuse me sir, would the ambiguous case in sine rule still apply if you're given a diagram? Say, you're given a diagram where the angle's clearly acute, but using the ambiguous case, the sine rule gives an obtuse angle solution as well (the angle sum of the triangle is still less than 180 degrees). In that case, do we just take the acute solution or both the obtuse and acute solution?
Thank you
Providing the obtuse solution takes a few seconds and you shouldn't be marked down for it especially if the diagram does not indicate that it is to scale.
Inverse sine gives acute angles by default. Inverse sine is defined assuming the domain of sine is restricted from -90deg to +90deg.
You know that the length of the sides over there sines are equal but you have not said what they are equal too
Eddie coming in clutch
Can I use the sine rule on right triangles?
yeah you can
Why are you dividing by sinASinB?
Behind the scene he wanted to prove that big sides go with big angle. However there was a mis match with the side and sine so he divided it.
What about a triangle with an obtuse triangle? The altitude will be outside of the triangle, so sine can’t be applied in the same way
The law of sines still applies to obtuse triangles. The one problem that will happen with obtuse triangles, that wouldn't otherwise happen with acute triangles, is that if you depend on using inverse sine, you could get the wrong answer, even if you set up the law of sines correctly. The reason is that inverse sine assumes the answer is between -90 deg and + 90 deg, hence it will give you the acute answer by default.
When the angle you are seeking is known to be obtuse because of other information in the problem, you'll have to "mirror image" your answer around 90 degrees. I.e. subtract it from 90 deg, and then add 90 deg. Because sin(90deg - theta) = sin(90deg + theta). An example is 60 degrees and 120 degrees, which both have the same sine.
subtract it from 90 then add 90 is a funny way of saying subtract it from 180 ahaha@@carultch
How old are the students ?
considering its high school math in Australia, probably not very. The sine rule is standard for year 12 students so roughly 16,17,18
It’s in the year 10 course too, so 14 + 15
5.3 year 10 i would assume
No no no no no. I am gonna call it the Si(n)gma Rule and you can't convince me otherwise!
This wrong!
no one argued with you.....
sorry Mr Woo......a terribly confusing explaination of a simple proof
Lol no