求值:sin10°-根号3乘cos10°/cos40°

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求值:sin10°-根号3乘cos10°/cos40°求值:sin10°-根号3乘cos10°/cos40°求值:sin10°-根号3乘cos10°/cos40°答:(sin10°-√3cos10°)

求值:sin10°-根号3乘cos10°/cos40°
求值:sin10°-根号3乘cos10°/cos40°

求值:sin10°-根号3乘cos10°/cos40°
答:
(sin10°-√3cos10°)/cos40°
=2*[(1/2)sin10°-(√3/2)cos10°]/cos40°
=2*[cos60°sin10°-sin60°cos10°)/cos40°
=2sin(10°-60°)/cos40°
=-2sin50°/sin50°
=-2