Question

Please help!
Verify:
-sinx=cos(pi/2+x)

Answer 1

cos ( pi/2 + x)

Do you know that cos function changes to sin at pi/2

and since it enters the second Quadrant, where cos is negative

So, as a result,
cos(pi/2 + x) = - sinx

Answer 2

how can I show the steps to solve this…and why does cos change to sin??? Ive never heard of that before at pi/2 cos is 0 and sin is 1 right?

Answer 3

isnt pi/2 between Quad 1 and Quad 2?

Answer 4

Yesh you are correct that at pi/2 sin is 1 and cos is 0

Yep you are correct there too when you said that pi/2 is the perpendicular line between quad 1 and quad 2...

But, did you notice that it says pi/2 + x ?

so.. adding a value x in pi/2 would make it any angle in the second quad...

Please note that, when such variable are given we talk about values between 0 to pi/2

Answer 5

Is the concept clear ?
Now lemme show you, how to verify it