Question

Verify the identity and explain how cot(x- pi/2)= -tan x

Answer 1

First, let's recall some usefull information:

- cot(x) = 1/tg(x) = cos(x)/sin(x)

- tan(x) = sin(x)/cos(x)

We also know that:

- cos(x - pi/2) = sin(x)

- sin(x - pi/2) = -cos(x)

Now we can use those relationships and get:

cot(x - pi/2) = cos(x - pi/2)/sin(x -pi/2) = sin(x)/-cos(x) = -tan(x)

So we have verified the identity, and explained step by step why the identity is true.