Упростить:
(cos18° cos7° - sin18°sin7°)² + (sin15° cos10° + cos15° sin10°)²
(cos18° cos7° - sin18°sin7°)² + (sin15° cos10° + cos15° sin10°)²
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(cos18° cos7° - sin18°sin7°)² + (sin15° cos10° + cos15° sin10°)²=
= (cos(18° + 7°))² + (sin(18° + 7°))² =
= cos² 25° + sin²25° = 1
В конце применили основное тождество: sin²α + cos²α = 1
Ответ: 1