把下列参数方程代为普通方程:① x=t^2,y=4t(t为参数)② x=sin2θ,y=sinθ+cosθ(θ为参数)

① x = t² (i)
y/4 = t (ii)
(ii)²:(y/4)² = t² (iii)
(i) = (iii):x = (y/4)²
x = y²/16
y² = 16x,(x ≥0)
② x = 2sinθcosθ (iv)
y = sinθ + cosθ (v)
(v)² :y² = (sinθ + cosθ)²
y² = sin²θ + 2sinθcosθ + cos²θ (sin²θ + cos²θ = 1)
y² = 1 + 2sinθcosθ (vi)
由(iv)代入(vi)式:得y² = 1 + x ( -1 ≤x ≤1)