Question

i need help with verifying cos(5x)/sin(x)+cos(5x)/cos(x)=cos(4x)/sin(x)cos(x)

Answer 1

re check the problem, I think you wrote something not correct. ( from the numerator)

Answer 2

I double checked .. its the same

Answer 3

what about this one
tan^-1(x)+tan^-1(1/x)=pi/2, x>0

Answer 4

I don't know, both :( I am sorry.

Answer 5

thanks for the thought

Answer 6

and this one
cos^-1(x)+cos^-1(-x)=pi

Answer 7

can you post a quick screenshot of the material?

Answer 8

do you know how to take a screenshot?

Answer 9

well.. anyhow ... \(\bf \cfrac{cos(5x)}{sin(x)}+\cfrac{cos(5x)}{cos(x)}=\cfrac{cos(4x)}{sin(x)cos(x)}\\\implies \cfrac{2cos(5x)}{sin(x)cos(x)}=\cfrac{cos(4x)}{sin(x)cos(x)}
\) withouth going further... I did a quick check if they match up.... so check the graph below here

Answer 10

anyhow.... in the end, they won't match, thus the identities aren't equal

Answer 11

thank you very much , did u check the others ?

Answer 12

this cos^-1(x)+cos^-1(-x)=pi
and this tan^-1(x)+tan^-1(1/x)=pi/2, x>0 ???

Answer 13

haven't.... need to dash in a few secs :(