Question

Помогите, пожалуйста. Очень надо! 

Answer 1

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)$2tg alpha *2 sqrt{ frac{1}{sin ^{2} alpha }-1 } =2tg alpha* 2ctg alpha = frac{2sin alpha *2cos alpha }{cos alpha *sin alpha } =4$