求sin-sin17°cos30°/cos17°的值

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求sin-sin17°cos30°/cos17°的值求sin-sin17°cos30°/cos17°的值求sin-sin17°cos30°/cos17°的值sin47=sin(30+17)=sin30

求sin-sin17°cos30°/cos17°的值
求sin-sin17°cos30°/cos17°的值

求sin-sin17°cos30°/cos17°的值
sin 47 =sin(30+17)=sin30cos17+sin17cos30
sin47-sin17*cos30/cos17
=(sin30cos17+sin17cos30-sin17*cos30)/cos17
=sin30cos17/cos17
=sin30
=1/2