Question

Express sin 67° + cos 75° in terms of trigonometric ratios of angles between 0° and 45°

Answer 1

∵ 23 = 90 – 67 & 15 = 90 – 75

∴ sin 67° + cos 75°

= sin (90 – 23)° + cos (90 – 15)°

= cos 23° + sin 15°.