求曲线x=sint y=cos2t 在t=π/6时应点处的切线f方程和与法线方程

dx/dt=costdy/dt=-2sin2ty'=(dy/dt)/(dx/dt)=-2sin2t/cost=-4sintt=π/6时,x==sin(π/6)=1/2,y=cos(π/3)=1/2y'=-4sin(π/6)=-4*1/2=-2因此切线方程为：y=-2(x-1/2)+1/2=-2x+3/2法线方程为：y=1/2*(x-1/2)+1/2=x/2+1...