Question

求过点(2,-1),倾斜角是直线4X+3Y+4=O的倾斜角一半的直线方程

Answer 1

所求直线倾斜角x,有a=2x

tana=-4/3=2tanx/(1-tanx^2)

tanx=-1/2或tanx=2

过点(2,-1),y=kx+b

-1=2*-1/2+b或-1=2*2+b

b=0,或b=-5

所求直线：x+2y=0或2x-y-5=0