求秒杀,
问题描述：
求秒杀,
1.化简：（tan10°- tan60°）cos10°/sin50°
2.山东2008高考题：已知cos(a-π/6)+sina=4/5√3,则sin(a+7π/6)的值是?
注：√是根号,π是圆周率pai.
答
1.(tan10°- tan60°)cos10°/sin50°=(sin10°/cos10°-√3 )cos10°/sin50°=(sin10°-√3cos10°)/sin50°=2[(1/2)sin10°-(√3/2)cos10°]/sin50°=2sin(10°-60°)/sin50°=-2 2.cos(a-π/6)+sina=cos(π/6)*co...