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Question
Express sin 67° + cos 75° in terms of trigonometric ratios of angles between 0° and 45°
Solution
∵ 23 = 90 – 67 & 15 = 90 – 75
∴ sin 67° + cos 75°
= sin (90 – 23)° + cos (90 – 15)°
= cos 23° + sin 15°.
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