Вычислите (3cos(π/2+a)+2sin(π-a))/(2cos(π+a)-3sin(3π/2+a)), если tga=4.

\[\frac{3\cos\left( \frac{\pi}{2} + a \right) + 2\sin(\pi - a)}{2\cos(\pi + a) - 3\sin\left( \frac{3\pi}{2} + a \right)} =\]

\[= \frac{- 3\sin a + 2\sin a}{- 2\cos a + 3\cos a} = \frac{- \sin a}{\cos a} =\]

\[= - tg\ a\]

\[tg\ a = 4:\]

\[- tg\ a = - 4.\]