Question

Find the exact values of the remaining five trigonometric functions of o satisfying the given conditions.

Answer 1

First, tan(θ) = sin(θ) / cos(θ), so if cos(θ) = 3/5 > 0 and tan(θ) < 0, then it follows that sin(θ) < 0.

Recall the Pythagorean identity:

sin²(θ) + cos²(θ) = 1

Then

sin(θ) = -√(1 - cos²(θ)) = -4/5

and so

tan(θ) = (-4/5) / (3/5) = -4/3

The remaining trig ratios are just reciprocals of the ones found already:

sec(θ) = 1/cos(θ) = 5/3

csc(θ) = 1/sin(θ) = -5/4

cot(θ) = 1/tan(θ) = -3/4