Упростить: (cos18° cos7° - sin18°sin7°)² + (sin15° cos10° + cos15° sin10°)²

Question

Упростить:
(cos18° cos7° - sin18°sin7°)² + (sin15° cos10° + cos15° sin10°)²

Answer 1

(Cos(18+7))^2+(sin(18+7))^2=1;