Can you clear up my confusion? This is on the exercise deriving the formula for the graph of h(x) and evaluating for cos. With a positive end point (-π/2,5) and a negative midpoint (π/4,-4) how is this not positive cos shifted left π/2 ? Also when you calculated from the end point to the mid point, how is that not just 1/2 the period? By my calculations the formula should be h(x)=4.5cos(4/3x+π/2)+.5 What am I not seeing? Thanks in advance.
@@khanmanmath3810Thank you. My confusion starts at 13:00 where you choose negative cos when the coordinates given seem to indicate positive cos should be formulated. Then at 14:22 you calculate the value of 1/2 the period, but use that value in your calculations as the full period. The program acknowledged your formulation as correct, so I am trying to understand what I'm missing.
Whew. Ok. You are correct that the period was miscalculated, but at 18:37 I did the correction on that. As far as the equation, you can use +cos or -cos and simply adjust the phase shift, so either one works. My way : the equation is -4.5 cos (4x/3 - pi/3) + 0.5 Your way : the equation is 4.5 cos (4x/3 + 2pi/3) +0.5 In the equation that you typed, you forgot to distribute 4/3. start with : 4.5 cos (4/3)*(x + pi/2) + 0.5 distribute 4/3 : 4.5 cos (4x/3 + 2pi/3) + 0.5
I HAVE BEEN STUCK ON THIS ACTIVITY FOR SO LONG. I haven’t watched the video yet, but i hope it helps. the one video example we khan gave us didn’t help enough.
i tried this method fir g(x)=0.5cos(1/3x+2pi/3)-2 and it did not work finding the period gave me 3/4pi which was incorrect anyway u could walk me through this one step by step? not sure where im getting confused at
The formula for period is (2 pi / b), where b is the coefficient of x. In your equation, b = 1/3. So (2 pi / (1/3)) = (2 pi) times 3 = 6 pi Remember that dividing by 1/3 is the same as multiplying by 3.
![Phase Shift of Sine & Cosine Graphs (Sinusoidal Waves) - [2-21-13]](/img/n.gif)
Idk why, but khan academy doesn’t seem to have a video explaining the phase shift. Thanks for the clarification
You got it! Hope it worked for you.
Can you clear up my confusion? This is on the exercise deriving the formula for the graph of h(x) and evaluating for cos. With a positive end point (-π/2,5) and a negative midpoint (π/4,-4) how is this not positive cos shifted left π/2 ? Also when you calculated from the end point to the mid point, how is that not just 1/2 the period?
By my calculations the formula should be h(x)=4.5cos(4/3x+π/2)+.5 What am I not seeing? Thanks in advance.
Please time stamp where the problem begins and I will get to it soon.
@@khanmanmath3810Thank you. My confusion starts at 13:00 where you choose negative cos when the coordinates given seem to indicate positive cos should be formulated. Then at 14:22 you calculate the value of 1/2 the period, but use that value in your calculations as the full period. The program acknowledged your formulation as correct, so I am trying to understand what I'm missing.
Whew. Ok. You are correct that the period was miscalculated, but at 18:37 I did the correction on that.
As far as the equation, you can use +cos or -cos and simply adjust the phase shift, so either one works.
My way : the equation is -4.5 cos (4x/3 - pi/3) + 0.5
Your way : the equation is 4.5 cos (4x/3 + 2pi/3) +0.5
In the equation that you typed, you forgot to distribute 4/3.
start with : 4.5 cos (4/3)*(x + pi/2) + 0.5
distribute 4/3 : 4.5 cos (4x/3 + 2pi/3) + 0.5
@@khanmanmath3810 I understand. Thank you for taking the time to clarify.
I HAVE BEEN STUCK ON THIS ACTIVITY FOR SO LONG. I haven’t watched the video yet, but i hope it helps. the one video example we khan gave us didn’t help enough.
No prob. Let me know how it goes!
came here because khan academy didnt explain phase shifting . or at least i didnt see it
Thanks for watching. Hope it helped. I think I may have even made a duplicate video for this exercise.
Same
Thank you so much!
You're welcome. Glad it helped!
i tried this method fir g(x)=0.5cos(1/3x+2pi/3)-2 and it did not work
finding the period gave me 3/4pi which was incorrect
anyway u could walk me through this one step by step? not sure where im getting confused at
The formula for period is (2 pi / b), where b is the coefficient of x.
In your equation, b = 1/3.
So (2 pi / (1/3)) = (2 pi) times 3 = 6 pi
Remember that dividing by 1/3 is the same as multiplying by 3.
@@khanmanmath3810 thank you
@@johnsingavarapu9308 No problem. Hope that helped.