12.
[tex]( { \frac{1}{2} })^{2} + ( { \frac{ \sqrt{3} }{2} }^{2} ) = \frac{1}{4} + \frac{3}{4} = \frac{4}{4} = 1[/tex]
13.
[tex] \frac{ \sqrt{2} }{2} + \frac{ \sqrt{2} }{2} = \frac{2 \sqrt{2} }{2} = \sqrt{2} [/tex]
