求[2sin50°+sin10°(1+√3tan10°0]sin80°的值

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求[2sin50°+sin10°(1+√3tan10°0]sin80°的值
求[2sin50°+sin10°(1+√3tan10°0]sin80°的值

求[2sin50°+sin10°(1+√3tan10°0]sin80°的值
原式=[2sin(60-10)+sin10+(√3)sin2(10)/cos10]sin(90-10) 用公式sin(A-B)=sinAcosB-cosAsinB
=[(√3)cos10-sin10+sin10+(√3)sin2(10)/cos10 ]cos10
=(√3)cos2(10)+(√3)sin2(10)
=(√3)[cos2(10)+sin2(10)] sin2A+cos2B=1
=√3

[2sin50°+sin10°(1+√3tan10°)]sin80°
=[2sin50°+sin10°(tan60°-tan10°)/tan50°]sin80°
=[2sin50°+sin10°cos50°(tan60°-tan10°)/sin50°]sin80°
=[2sin50°+sin10°cos50°(sin60°/cos60°-sin10°/cos10°)/sin...

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[2sin50°+sin10°(1+√3tan10°)]sin80°
=[2sin50°+sin10°(tan60°-tan10°)/tan50°]sin80°
=[2sin50°+sin10°cos50°(tan60°-tan10°)/sin50°]sin80°
=[2sin50°+sin10°cos50°(sin60°/cos60°-sin10°/cos10°)/sin50°]sin80°
=[2sin50°+sin10°cos50°(sin60°cos10°-cos60°sin10°)/(sin50°cos10°cos60°)]sin80°
=[2sin50°+sin10°cos50°sin50°/(sin50°cos10°cos60°)]sin80°
=[2sin50°+sin10°cos50°/(cos10°cos60°)]sin80°
=[2sin50°+sin10°cos50°/(cos10°cos60°)]cos10°
=2sin50°cos10°+2sin10°cos50°
=2sin(50°+10°)
=√3

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