题目应该是
sin22°+ cos30°sin8°
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cos22°- sin30°sin8°
sin22°=sin(30°-8°)=sin30°*cos8°-cos30°*sin8°
sin22°+ cos30°sin8°=sin30°*cos8°
cos22°=cos(30°-8°)=sin30°*sin8°+cos30°*cos8°
cos22°- sin30°sin8°=cos30°*cos8°
分子除以分母得：sin30°*cos8°/cos30°*cos8°=sin30°/cos30°=tan30°=√3 /3