3 The parametric equations of a curve are
$$x = \sin \theta , \quad y = \sin 2 \theta , \quad \text { for } 0 \leqslant \theta \leqslant 2 \pi .$$
- Find the exact value of the gradient of the curve at the point where \(\theta = \frac { 1 } { 6 } \pi\).
- Show that the cartesian equation of the curve is \(y ^ { 2 } = 4 x ^ { 2 } - 4 x ^ { 4 }\).