is an identity.
Here's a nice proof of the angle sum identity for cosine:
And in the case where then that gives
Q.E.D.
EDIT: I actually went back and re watched the video a few times and realized that he disengaged the bottom two functions. I'm sorry if this took up anyone's time. Can anyone tell me how to graph functions simultaneously on a graphing calculator?
Hi. I'm following along on a precalculus video from my professor. In the very first problem, he graphs a trigonometric equation in the calculator to see if it is an identity. I'm not getting the same graph as he is, and I'm not sure what's wrong. I have it on zoom trig but my graph is different than his.
This is the problem:
Is cos2x = 2(cosx^2)-1 an identity?
Here is the video. It's the very first problem he covers.
Thanks in advance. Please let me know if you need more information.
is an identity.
Here's a nice proof of the angle sum identity for cosine:
And in the case where then that gives
Q.E.D.