tan2A=4/3,求tanA

问题描述:

tan2A=4/3,求tanA

tan2A=2tanA/[1-(tanA)^2]=4/3
2-2(tanA)^2=3tanA
2(tanA)^2+3tanA-2=0
(2tanA-1)(tanA+2)=0
tanA=1/2或者-2