Если ctga=15/8, тогда tga, cosa, sina=? Помогиите

tga=1/ctga=8/15 cosa/sina=15/81+tg^2a=1/cos^2a1+64/225=1/cos^2a1 64/225=1/cos^2a^289/225=1/cos^2a1/cosa=17/15cosa=15/17sin^2a=1-225/289sina=8/17