Дианчик0444 1)sin2° cos28°+sin28°cos2°=sin(2°+28°)=sin30°=1/2
2)cos73° cos13°+ sin73° sin13°=cos(73°-13°)=cos60°=1/2
3)sin50° sin5°+cos50°cos5°=cos(50°-5°)=cos45°=√2/2
4)cos 3π/8 sin5π/24 - cos 5π/24 sin3π/8=sin(3π/8 - 5π/24)=sin π/6=sin 30°=1/2
5)cos100°sin10°-sin100°cos10°=sin (100° -10°)=sin 90°=1
6)cos170°sin35°-cos35°sin170°=sin(170°-35°)=sin 135°=√2/2
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8)sin105°sin75°+sin15°cos105°=sin105°sin75°+sin(90°-75°)cos105°=sin105°sin75°+cos75°cos105°=cos(105°-75°)=cos30°=√3/2
9)cos20°cos25°-cos70°sin25°=cos20°cos25°-cos(90°-20°)sin25°=cos20°cos25°-sin20°sin25=cos(20°+25°)=cos45°=√2/2
10)cos 43 cos17-cos47cos(-73)=cos43 cos17-cos(90-43)cos(90-17)=cos 43 cos17-sin43 sin17=cos(43+17)=cos60°=1/2