If cos⁻¹x = sin⁻¹x, then which one of the following is correct?
Answer
The correct answer is C: x = 1/√2. cos⁻¹x + sin⁻¹x = π/2 for all x ∈ [–1, 1]. If cos⁻¹x = sin⁻¹x, then 2sin⁻¹x = π/2, so sin⁻¹x = π/4, giving x = sin(π/4) = 1/√2.
A.x = 1
B.x = 1/2
C.x = 1/√2✓ Correct
D.x = 1/√3
Explanation
cos⁻¹x + sin⁻¹x = π/2 for all x ∈ [–1, 1]. If cos⁻¹x = sin⁻¹x, then 2sin⁻¹x = π/2, so sin⁻¹x = π/4, giving x = sin(π/4) = 1/√2.
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