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Answer each of the following questions in one word or one sentence or as per exact requirement of the question:
Write the value of cos–1(cos 1540°).
Given cos-1 (cos 1540°)
= cos-1{cos (1440° + 100°)}
= cos-1{cos (360° × 4 + 100°)}
We know that cos (2π + θ) = cos θ
= cos-1{cos 100°}
We know that cos-1 (cos θ) = θ if θ ∈ [0, π]
= 100°
∴ cos-1 (cos 1540°) = 100°