Question

If `tan theta = 24/7`, `180 < theta < 270` how do you find `cos theta`?

Answer 1

`-7/25`

Explanation:

`theta` is in the third quadrant wherein tan is positive and both sin

and cos are negative.

`tan theta = 24/7 = sin theta/cos theta =sqrt(1-cos^2theta)/cos theta`

Squaring and solving, `cos theta= +-7/25.`.

Positive root is inadmissible.