Question

Обчисліть cos²15°- sin²15°

Answer 1

Ответ:

cos²15°- sin²15° = cos(2×15)° = cos 30° = √3/2

cos²x - sin²x = cos2x

Answer 2

cos² 15° - sin² 15°

= cos 2(15°)

= cos 30°

= 1/2 √3