Convert $\sin\theta/2$ using trig identities $$\sin\dfrac \theta2 = \sin^2θ+\cos^2θ-1$$
$$\sinθ = 2\sin^2θ+\cos^2θ-1$$
Am I on the right track?

In the event that you are being asked to solve for $\theta$ given the equation $$\sin\left(\frac \theta2\right) = \sin^2 \theta + \cos^2 \theta - 1,$$
...note that by the Pythagorean Theorem, we know that $\sin^2 \theta + \cos^2 \theta = 1.\;$
$$\begin{align}\sin\left(\frac \theta2\right) & = \underbrace{(\sin^2 \theta + \cos^2\theta)}_{= 1} - 1 \\ \\ & = 1 - 1 \\ \\& = 0\end{align}$$
$$\implies \frac{\theta}{2} = \sin^{-1}(0) \implies \theta = 2 \sin^{-1}(0)$$
