Question 13
Let $x$ be a real number such that
$$\frac{\sin^4x+\cos^4x}{\sin^2x+\cos^4x}=\frac8{11}.$$
Assuming $\sin^2x\gt 1/2$, find the value of $\sqrt{28}(\sin^4x-\cos^4x)$.
$$\frac{\sin^4x+\cos^4x}{\sin^2x+\cos^4x}=\frac8{11}.$$
Assuming $\sin^2x\gt 1/2$, find the value of $\sqrt{28}(\sin^4x-\cos^4x)$.