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Cos²60°+sin²60°答案

cos²60° +sin²60° =(2分之1)²+(2分之根号3)² =4分之1+4分之3 =1 很高兴为您解答,祝你学习进步! 如果我的回答对你有帮助,请及时选为满意答案,谢谢~~

题目缺少运算符,只能猜着做: sin²20°+cos²80°+√3sin20°cos80° =(1-cos40°)/2+(1-cos160°)/2+(√3/2)(sin100°-sin60°) =1-cos100°cos60°+(√3/2)sin100°-3/4 =1/4-(1/2)cos100°+(√3/2)sin100° =1/4+sin(100°+30°) =1/4+sin130° =1/2+sin...

(sinA)^2=(1/2)(cos(B-C)-cos(B加C))=(1/2)(cos(B-C)加cosA),A=60,将A正弦余弦代入,得cos(B-C)=1,B=C=60度 (2)由正弦定理,a^2=bc,由余弦a^2=b^2加c^2-2bccosA,得cosA=(a^2加b^2-1)/2>(2bc-1)/2=1/2,所以sinA最大为(根号3)/2,S=0.5bcsi...

倒数关系: tanα ·cotα=1 sinα ·cscα=1 cosα ·secα=1 商的关系: sinα/cosα=tanα=secα/cscα ...

解答: (1)∵a=(cosα,sinα),b=(cosβ,sinβ) ∴ |a|=√(cos²α+sin²α)=1 |b|=√(cos²β+sin²β)=1 ∴ (a+b).(a-b)=a²-b²=1-1=0 ∴ (a+b)⊥(a-b) (2)∵a=(cosα,sinα),b=(cosβ,sinβ) ∴ a.b=cosαcosβ+sinαsinβ=cos(α-β)...

向量OC=x*OA+y*OB,设向量OC与OA的夹角为θ(0°≤θ≤120°); x/sin(180°-60°-θ)=1/sin60°,x=sin(120°-θ)/sin60°;y/sinθ=1/...

sin²30°+cos²30°=1 tan45°=1 cot60°=根号3/3 ∴ 原式=1+根号3

1)2sin²60°-√3tan30°-2cos²45° =2(√3/2)²-√3×*√3/3-2(√2/2)² =3/2-1-1 =-1/2 2)√2×sin45°+√3×cos30°-3/2 =√2×√2/2+√3×√3/2-3/2 =1+3/2-3/2 =1 -2三次方 × 2负一次方 +根号12 除以 (tan30°-cos45°) =-8×1/2+√12/(√3/3-√2/...

∫cos³x/(1+sin²x)dx=∫cos²x/(1+sin²x)dsinx =∫(1-sin²x)/(1+sin²x)dsinx =∫2/(1+sin²x)-1dsinx =2arctansinx-sinx+C

=√2x√3/2-4x3/4+√2/2x√3 =√6-3

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