Let cos (-θ) = -3/5 and tanθ>0.

What is the value of sin (-θ) ?

A. - 4/5

B. 4/3

C. - 3/5

D. 4/5

A

Step-by-step explanation:

The cosine of a right triangle is the adjacent over the hypotenuse. If the cosine is - 3/5 then it must be a right triangle with sides 3, 4, & 5 since this is a Pythagorean triple. This means the sin will be - 4/5. We know its negative because the tangent is positive so this is the 3rd quadrant where both Sine and Cosine are negative.