Задача 46920 ...

katya34

2020-04-13 14:27:09

Найти tg^2 β, если 7sin^2 β + 9cos^2 β = 2

sova

2020-04-13 15:49:01

★

7sin^2β + 9cos^2β = 2*[b]1[/b]

Так как
[b]1[/b]=sin^2 β +cos^2 β


7sin^2β + 9cos^2β = 2*(sin^2 β +cos^2 β )

5sin^2 β =-7cos^2 β ⇒ 5tg^2 β =-7 ⇒ [b]tg^2 β =-7/5[/b]