Which of the following is/are TRUE ?`2 sin^2 alpha+cos 2 alpha=1`

For hyperbola x^2/(cos^2alpha)-y^2/(sin^2alpha)=1 which of the following remains constant with change in alpha

Which of the following is independent of alpha in the hyperbola (0 < alpha < pi/2)x^2/cos^2 alpha-y^2/sin^2alpha=1

For the hyperbola x^2/(cos^2alpha)-y^2/(sin^2alpha)=1 , which of the following remains constant when alpha varies ?

Prove the following identities: (1-sin alpha+cosalpha)^2=2(1+cos alpha)(1-sin alpha)

For the hyperbola (x^(2))/( cos ^(2) alpha ) -(y^(2))/( sin ^(2) alpha ) =1 Which of the following remains constant when alpha varies ?

For the hyperbola (x^(2))/( cos ^(2) alpha ) -(y^(2))/(sin^(2) alpha ) =1 ,which of the following remains constant when alpha varies?

For the hyperbola x^2/ cos^2 alpha - y^2 /sin^2 alpha = 1 which of the following remains constant when alpha varies?

Which is equivalent to (sin^2 alpha + cos^2 alpha )/(cos alpha ) ?