x=arctant=π/4
y=1+t^3=2
所以參數(shù)t=1
切線斜率
dy/dx
=(dy/dt)/(dx/dt)
=(arctant)'/(1+t^3)'
=(1/(1+t^2))/(1+3t^2)
=1/[(1+t^2)(1+3t^2)]
t=1時(shí) dy/dx=1/8
點(diǎn)斜式
y-2=1/8(x-π/4)
8y-16=x-π/4
x-8y-π/4+16=0