Question

sin36°+sin15°sin39°/cos36°–cos15°sin39°求值详细的过程，谢谢

sin36°+sin15°sin39°/cos36°–cos15°sin39°求值详细的过程，谢谢啦

Answer 1

(sin36°+sin15°sin39°)/(cos36°-cos15°sin39°)
=[sin36°+(cos24°-cos54°)/2]/[cos36°-(sin54°+sin24°)/2]
=(2sin36°+cos24°-sin36°)/(2sin54°-sin54°-sin24°)
=(sin36°+cos24°)/(sin54°-sin24°)
=(sin36°+sin66°)/(sin54°-sin24°)
=(2sin51°cos15°)/(2cos39°sin15°)
=(2cos39°cos15°)/(2cos39sin15°)
=cos15°/sin15°
=sin75°/cos75°
=tan75°
=tan(45°+30°)
=(tan45°+tan30°)/(1-tan45°tan30°)
=(1+√3/3)/(1-√3/3)
=2+√3。

Answer 2

直接按计算器吧。