Question

27sin2a/√2, здесь ctg=-2√2.

Answer 1

$ctga= \frac{cosa}{sina} =-2 \sqrt{2} \\ \\ (\frac{cosa}{sina} )^2=(-2 \sqrt{2} )^2=8 \\ \\ sin^{2}a +cos^{2}a=1 \\ \\ cos^{2}a=1-sin^{2}a \\ \\ \frac{1- sin^{2} a}{ sin^{2}a } =8 \\ \\ sin^{2}a= \frac{1}{9} \\ \\ \frac{27sin2a}{ \sqrt{2} } =27 \sqrt{2} sinacosa=27 \sqrt{2} sinacosa*sina/sina= \\ \\ 27 \sqrt{2} sin^{2} a*ctga=27 \sqrt{2} * \frac{1}{9} *(-2 \sqrt{2} )=-12$