Question

Verify tan(x + pi/2) = -cotx

Answer 1

tan ( x+ pi/2) = tan ( 90 + x)

since the angle is in the second quadrant .where tan is negative. thus the negative sign.

and the angle from the horizontal is 180-(90+x) =90-x..hence it changes to cot

therefore tan(90=x) = - cotx

Answer 2

thanks

Answer 3

To cut out on the theory, mathematically you can prove it like this :

tan(pi/2 +x) = tan(pi/2 - (-x)) = cot(-x) = -cotx

Answer 4

i think u need some other method, the very basic method ?