You can solve for
, then take square roots:
![2\sin^2\theta=1\implies\sin^2\theta=\frac12\implies\sin\theta=\pm\frac1{\sqrt2}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/eamxubjswqmpkjjg6gcb6d58w8552fc1mt.png)
Then
![\theta=\frac\pi4+2n\pi,\frac{3\pi}4+2n\pi,-\frac\pi4+2n\pi,\text{ or }-\frac{3\pi}4+2n\pi](https://img.qammunity.org/2020/formulas/mathematics/middle-school/5a5epogemjd0hm2abcdsn6597tmx7c2rm7.png)
where
is any integer; we get the following solutions in the interval
:
![\boxed{\theta=\frac\pi4,\frac{3\pi}4,\frac{5\pi}4,\frac{7\pi}4}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/s70t6bcptz61z5vwybn6xfyxn9pylek5qt.png)
Or, you can use the double angle identity:
![\sin^2\theta=\frac{1-\cos(2\theta)}2=\frac12\implies1-\cos(2\theta)=1\implies\cos(2\theta)=0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1ts3t5zls9zlx91c9iktb8ikrc3o9uomfl.png)
Then
![2\theta=\frac\pi2+n\pi\implies\theta=\frac\pi4+\frac{n\pi}2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xubv46l2eazltfuduzm2wtkw9okmxdcpdn.png)
where
is any integer, and we get the same solutions as above within the prescribed interval.