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Find the value of (cos x + cos y) (sin x – sin y) / (cos x – cos y) (sin x + sin y), where x = 90° and y = 0°.

Find the value of (cos x + cos y) (sin x – sin y) / (cos x – cos y) (sin x + sin y), where x = 90° and y = 0°. Correct Answer -1

(cos x + cos y) (sin x – sin y) / (cos x – cos y) (sin x + sin y),

Putting x = 90° and y = 0°

⇒ (0 + 1)(1 – 0) / (0 – 1)(1 – 0)

∴ (cos x + cos y) (sin x – sin y) / (cos x – cos y) (sin x + sin y) = -1

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