Mohon bantuannya ya. Terima kasih sebelumnya :)

[tex] \frac{ \cos(225) + \cos(15) }{ \sin(225) + \sin(15) } \\ = \frac{2 \cos( \frac{a + b}{2} ) \cos( \frac{a - b}{2} ) }{2 \sin( \frac{a + b}{2}) \cos( \frac{a - b}{2} ) } \\ = \frac{2 \cos( \frac{225 + 15}{2} ) \cos( \frac{225 - 15}{2} ) }{2 \sin( \frac{225 + 15}{2} ) \cos( \frac{225 - 15}{?} ) } \\ = \frac{2 \cos(120) \cos(105) }{2 \sin(120) \cos(105) } \\ = \frac{2 \cos(120) }{2 \sin(120) } \\ = \frac{2( - \frac{ 1}{2}) }{2( \frac{1}{2} \sqrt{3} )} \\ = \frac{ - 1}{ \sqrt{3} } \\ = - \frac{1 }{ \sqrt{3} } \times \frac{ \sqrt{3} }{ \sqrt{3} } \\ = \frac{ - \sqrt{3} }{ \sqrt{9} } \\ = \frac{ - \sqrt{3} }{3} \\ = - \frac{1}{3} \sqrt{3} [/tex]
Semoga dapat dipahami