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Sweetygirll72
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Urgent!!! Calculați :
Cos 15° =? Sin 105° = ?

Răspuns :

Criss779
cos 15°=cos(45°-30°)=cos45°×cos30°+sin45°×sin30°=√2÷2×√3÷2 + 1÷2×√2÷2=√6÷4+√2÷4=(√6+√2)÷4
sin 105°=sin(60°+45°)=sin60°×cos45°+sin45°×cos60°=√3÷2×√2÷2+√2÷2×1÷2=√6÷4+√2÷4=(√6+√2)÷4