Помогите, пожалуйста. Очень надо!

1) $sin \alpha = \frac{8}{17} cos \alpha = \sqrt{1- \frac{64}{289} } = - \frac{15}{17} tg \alpha =-\frac{8}{15}$
2) cos $cos ^{4} \alpha +sin ^{2} \alpha *cos ^{2} \alpha = cos ^{4} \alpha+(1-cos ^{2} \alpha )cos ^{2} \alpha=cos ^{4} \alpha+cos ^{2} \alpha-cos ^{4} \alpha=cos ^{2} \alpha$
3) $\frac{cos ^{2}62к+cos ^{2}28к }{4} - \frac{1}{2} cos60к= \frac{-cos^{2}28к+cos ^{2}28к}{4} - \frac{1}{2} * \frac{1}{2} =- \frac{1}{4}$
4) $\frac{1-tg ^{2} \alpha }{3+ctg^{2} \beta } -cos( \frac{ \pi }{2}+ \alpha )= \frac{1-tg ^{2} \alpha }{3+ctg^{2} \beta }-sin \alpha = \frac{1- \frac{1}{3} }{3+ \frac{1}{3} } - \frac{1}{2} =-0.3$
5) $2tg \alpha *2 \sqrt{ \frac{1}{sin ^{2} \alpha }-1 } =2tg \alpha* 2ctg \alpha = \frac{2sin \alpha *2cos \alpha }{cos \alpha *sin \alpha } =4$