1.sin²40°+sin²50°等于多少1.sin²40°+sin²50°等于多少,2.如何证明sin(30°+α)=cos(60°-α)
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1.sin²40°+sin²50°等于多少1.sin²40°+sin²50°等于多少,2.如何证明sin(30°+α)=cos(60°-α)
1.sin²40°+sin²50°等于多少
1.sin²40°+sin²50°等于多少,2.如何证明sin(30°+α)=cos(60°-α)
1.sin²40°+sin²50°等于多少1.sin²40°+sin²50°等于多少,2.如何证明sin(30°+α)=cos(60°-α)
1.sin²40°+sin²50°
sin²40°+sin²50°
=sin²40°+cos²(90°-50°)
=sin²40°+cos²40°
=1
2.如何证明sin(30°+α)=cos(60°-α)
sin(30°+α)
=cos[90°-(30°+α)]
=cos(60°-α)
1. sin²40°+sin²50°= sin²40°+cos²(90°-50°)=1
2.证明:sin(30°+α)=cos(90°-30°-α)
=cos(60°-α)
1.sin²40°+sin²50°=sin²40°+cos²40°=1【利用:sinA=cos(90°-A)】
2.sin(30°+α)=cos[90°-(30°+α)]=cos(60°-α)
祝你好运O(∩_∩)O~
sin²40°+sin²50° = sin²(90-50)+sin²50°=cos²50 +sin²50°=1
根据sin(x)= cos(90-x)
sin(30°+α)= cos(90-(30°+α))=cos(60°-α) 得证