Question

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

Answer 1

A

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.