(tan10+tan50+tan120)/(tan10tan50tan120)的值是?
问题描述:
(tan10+tan50+tan120)/(tan10tan50tan120)的值是?
答
∵tan60=(tan50+tan10)/(1-tan50*tan10) ∴tan50+tan10=tan60-tan60*tan50*tan10 又tan120+tan60=0 ∴tan50+tan10+tan120=tan60-tan60*tan50*tan10+tan120=-tan60*tan50*tan10=tan120*tan50*tan10 ∴(tan10+tan5...