Question

Evaluate cos(-θ) given that cosθ = -2/7.
a) 2/7
b) -2/7
c) 1/2
d) -1/2

Answer 1

To evaluate cos(-θ) given cosθ = -2/7, we can use the property that cosine function is an even function, which means cos(-θ) = cos(θ). Therefore, the answer is -2/7.

Step-by-step explanation:

To evaluate cos(-θ), we can use the property that cosine function is an even function, which means cos(-θ) = cos(θ). Since cosθ = -2/7, we can substitute the value of θ into the equation to get cos(-θ) = cos(θ) = -2/7. Therefore, the answer is option b) -2/7.The question asks to evaluate cos(-θ) given that cosθ = -2/7. In trigonometry, the cosine function is even, which means that cos(-θ) = cos(θ). Therefore, regardless of the sign of the angle, the value of the cosine of that angle remains the same.

Knowing that cosθ is -2/7, we can immediately conclude that cos(-θ) must also be -2/7. The correct answer is b) -2/7.