Question

Assertion (A) : cos⁻¹(cos(13π/6)) is equal to π/6. Reason (R) : The range of the principal value branch of the function y = cos⁻¹ x is [0, π].

Simplify : cos⁻¹x + cos⁻¹[x/2 + √(3 – 3x²)/2]; 1/2 ≤ x ≤ 1

cos–1 (1/2) + 2 sin–1 (1/2)

3cos–1 x = cos–1 (4x³ – 3x), x ∈ [1/2, 1]