Question

Помогите с алгеброй пже, 304(а); 306

Answer 1

$( frac{1}{1+Ctg ^{2} alpha}+Cos ^{2} alpha )*tg ^{2} alpha =( frac{1}{ frac{1}{Sin ^{2} alpha } } +Cos ^{2} alpha)*tg ^{2} alpha =$$(Sin ^{2} alpha +Cos ^{2} alpha )*tg ^{2} alpha =1*tg ^{2} alpha =tg ^{2} alpha$


$1+tg ^{2} alpha = frac{1}{Cos ^{2} alpha }\\tg ^{2} alpha = frac{1}{ frac{4}{5} } -1= frac{5}{4} -1= frac{1}{4} \\tg alpha = frac{1}{2}$

Answer 2

спасибо!

Answer 3

306)cosa=2/√5;0<a<π/2
tga=?
sina=√1-cos^2(a)=√1-4/5=1/√5
tga=sina/cosa=1/√5:2/√5=1/2

Answer 4

спасибо!