sin50°cos5°-sin20°/cos15°cos5°-cos20°
问题描述：
sin50°cos5°-sin20°/cos15°cos5°-cos20°
答
sin(50) = -0.26237485370393
cos5°-sin20°=-0.6292830652644
cos(15) = -0.75968791285882
cos5°-cos20=-0.12441987635016