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Question
Express (sin 67° + cos 75°) in terms of trigonometric ratios of the angle between 0° and 45°.
Solution
(sin 67° + cos 75°)
= (sin (90°−23°) + cos (90°−15°)) .....(∵ sin(90°−θ) = cosθ and cos(90°−θ) = sinθ)
= (cos 23°+ sin 15°)
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