Question

cos^–1(cos10) is equal to ______.

Options

• 4π + 10

• 4π – 10

• –4π + 10

• 10

Answer 1

cos^–1(cos10) is equal to 4π – 10.

Explanation:

cos^–1(cos10)

∵ cos^–1cosθ = θ if 0 ≤ θ ≤ π

⇒ cos^–1(cos(4π – 10)) = 4π – 10