x'(t) = -sint + 2cost(-sint) = -sint - sin2t
y'(t) = cost
t= π/4点处的切线斜率k = y'(t)/x'(t)
t= π/4点处的法线斜率k' = -1/k = -x'(x)/y'(t) = (sint + sin2t)/cost = (√2/2 + 1)/(√2/2) = √2 + 1