已知sinθ=3/5,cosθ=-4/5,则tan2θ=

问题描述:

已知sinθ=3/5,cosθ=-4/5,则tan2θ=

sinθ=3/5,cosθ=-4/5
tanθ=-3/4
tan2θ=2tanθ/(1-tan^2 θ)
=(-3/2)/(1-9/16)
=(-3/2)/(7/16)
=-24/7