5(1-cos²α) +13cos²α=6
5-5cos²α+13cos²α=6
8cos²α=1
cos²α=1\8
5sin²α+13(1-sin²α)=6
5sin²α+13-13sin²α=6
-8sin²α=-7
sin²α=7/8
tg²α=(1/8)/(7/8)=1/7
5(1-cos²α) +13cos²α=6
5-5cos²α+13cos²α=6
8cos²α=1
cos²α=1\8
5sin²α+13(1-sin²α)=6
5sin²α+13-13sin²α=6
-8sin²α=-7
sin²α=7/8
tg²α=(1/8)/(7/8)=1/7