- Thread starter
- #1

#### karush

##### Well-known member

- Jan 31, 2012

- 2,886

$\displaystyle\cos{\theta}+\sin{\theta}=\frac{ \sqrt{6} }{2}$

$\displaystyle(\cos{\theta}+\sin{\theta})^2=\frac{3}{2}$

$\displaystyle\cos^2{\theta}+2cos\theta\sin\theta+\sin{\theta}^2=\frac{3}{2}$

$\displaystyle\sin{2\theta}=\frac{1}{2}

\Rightarrow

\theta=\frac{\pi}{12}=15^o

$

the other answer is $75^o$ but don't know how you get it.