Question

Suppose sin(x) = -3/5 and cos(x) < 0. What the value of cos(2x)?

Answer 1

Answer:

The value of cos(2x) = 7/25

Hence, option C is true.

Step-by-step explanation:

Using the trigonometric identity

cos 2x = 1 - 2sin²x

Given

• sin(x) = -3/5

• cos(x) < 0

so substituting the values

cos 2x = 1 - 2sin²x

           = 1 - 2 (-3/5)²

           = 1 - 2 (9/25)

           = 1 - 18/25

           = 7/25

Therefore,

The value of cos(2x) = 7/25

Hence, option C is true.