sin10-cos20/cos10-sin20等于多少
问题描述:
sin10-cos20/cos10-sin20等于多少
答
(sin10°-cos20°)/(c0s10°-sin20°)=(cos80°-cos20°)/(sin80°-sin20°)
{把80°拆为50°+30°,20°拆为50°-30°}
=2sin50°sin30°/2sin50°cos30°=根号3/3