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sin90grade+cos270grade-sin la patrat 15grade

Răspuns :

1+0-sin²15°
sin15°=sin(45°-30°)=√2/2*√3/2-1/2*√2/2=(√6-√2)/4
sin²15°=(6+2-2*3√2)/16=(8-6√2)/16=1/2-3√2/8
1+1/2-3√2/8=3/2-(3√2)/8= (12-3√2)/8