sin^2a=1-cos^2a 5(1-cos^2a)+13cos^2a=6 ; 5-5cos^2a+13cos^2a=6 ; 8cos^2a=1 ; cos^2a=1/8 cos^2a=1-sin^2a 5sin^2a+13(1-sin^2a)=6 ; 5sin^2a+13-13sin^2a=6 ; -8sin^2a=-7 ; sin^2a=7/8 т.к tg^2=sin^2a/cos^2a => tg^2=1/8 * 8/7=7 Ответ: tg^2=7
