sin45cos60+sin30cos45

xzq76210002022-10-04 11:39:541条回答

sin45*cos60+sin30*cos45
请用二角和与差的方式解答，

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WOAINI201 共回答了12个问题 | 采纳率100%: sin45*cos60+sin30*cos45
=1/2[sin(45+60)+sin(45-60)]+1/2[sin(30+45)+sin(30-45)]
=1/2[sin105+sin(-15)]+1/2[sin75+sin(-15)]
=1/2[sin75-sin15]+1/2[sin75-sin15]
=sin75-sin15
=2[cos(75+15)/2][sin(75-15)/2]
=2cos45sin30
=2*[(根号2)/2]*(1/2)
=(根号2)/2; 1年前

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