已知tan80°=k,则sin100°的值等于?
问题描述：
已知tan80°=k,则sin100°的值等于?
答
00tan80°=-tan(180°-80°)=-tan100°=ktan100°=sin100°/cos100°=-kcos100°=sin100°/(-k)sin²100°+cos°100=1sin²100°+[sin100°/(-k)]²=1[(k²+ 1)/k²]sin²100°=1sin²1...