[tex] \frac{ \frac{sina}{cosa} + \frac{cosa}{cosa} }{ \frac{cosa}{sina} + \frac{sina}{sina} } =
7( a - 4)² + ( 4 - a) = 7(a - 4)² - (a -4) = ( a - 4)(7(a - 4) - 1)=(a - 4)(7a - 28 - 1)=
= ( a- 4)( 7a - 29)
<span>
3√5/4*5=3√5/20</span>
<span /><span>ответ:3√5/20</span>