The equation of normal to a curve at a point is given by the formula:
\[
y - y_0 = -\frac{1}{f'(x_0)} (x - x_0)
\]
where \( f'(x_0) \) is the derivative of the curve at the point \( (x_0, y_0) \).
1. First, differentiate the equation of the curve implicitly to find the slope of the tangent at \( x = 0 \). For the given equation, \( y = (1 + x)^y + \sin^{-1}(\sin^2 x) \), we need to differentiate both sides with respect to \( x \), considering implicit differentiation:
\[
\frac{d}{dx} \left( (1 + x)^y \right) + \frac{d}{dx} \left( \sin^{-1}(\sin^2 x) \right)
\]
2. After differentiating and solving, substitute \( x = 0 \) to get the slope of the normal. Finally, we can determine the equation of the normal, which is \( x + y = 1 \).