You should know that the values of sin and cos in the third quadrant are negative, hence the values of tan and cot are positive.

You need to use the basic trigonometric formula such that:

`sin^2x + cos^2x = 1 =gt cos x = - sqrt(1 - sin ^2x)`

Plugging sin x =`-3/5` in the formula above yields:

`cos x = - sqrt(1 - (-3/5)^2) =gt cos x = -sqrt(16/25) =gt cos x = -4/5`

You should use the following formula...

(The entire section contains 2 answers and 221 words.)

## Unlock This Answer Now

Start your **48-hour free trial** to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Already a member? Log in here.