sin9°cos15°-sin24°/sin9°sin15°+cos24°的值为___
问题描述:
sin9°cos15°-sin24°/sin9°sin15°+cos24°的值为___
答
0.3917083927
答
sin9°cos15°-sin24°/sin9°sin15°+cos24°=sin9°cos15°-sin(9°+15°)/sin9°sin15°+cos(9°+15°)=sin9°cos15°-sin9°cos15°-cos9°sin15°/sin9°sin15°+cos9°cos15°-sin9°sin15°=-cos9°sin15°/c...