(a) Start with the given equation:
\(\sin 2\theta + \cos 2\theta = 2 \sin^2 \theta\)
Using double angle identities, we have:
\(\sin 2\theta = 2 \sin \theta \cos \theta\)
\(\cos 2\theta = \cos^2 \theta - \sin^2 \theta\)
Substitute these into the equation:
\(2 \sin \theta \cos \theta + \cos^2 \theta - \sin^2 \theta = 2 \sin^2 \theta\)
Rearrange terms:
\(\cos^2 \theta + 2 \sin \theta \cos \theta - 3 \sin^2 \theta = 0\)
(b) Factor the equation:
\((\cos \theta - \sin \theta)(\cos \theta + 3 \sin \theta) = 0\)
Set each factor to zero:
\(\cos \theta - \sin \theta = 0\)
\(\tan \theta = 1\)
\(\theta = 45^\circ\)
And:
\(\cos \theta + 3 \sin \theta = 0\)
\(\tan \theta = -\frac{1}{3}\)
\(\theta \approx 161.6^\circ\)
Thus, the solutions are \(\theta = 45^\circ\) and \(\theta \approx 161.6^\circ\).