If `cos^4x/cos^2y+sin^4x/sin^2y=1` then prove that `cos^4y/cos^2x+sin^4y/sin^2x=1`

If cos^4x/cos^2y+sin^4x/sin^2y=1 ,show that cos^4y/cos^2x+sin^4y/sin^2x=1

If cos^4x/cos^2y+sin^4x/sin^2y=1 ,show that cos^4y/cos^2x+sin^4y/sin^2x=1

If (cos^4x)/(cos^2y)+(sin^4x)/(sin^2y)=1,"show taht", (cos^4y)/(cos^2x)+(sin^4y)/(sin^2x)=1

If (cos^(4)x)/(cos^(2)y)+(sin^(4)x)/(sin^(2)y)=1 , then (cos^(4)y)/(cos^(2)x)+(sin^(4)y)/(sin^(2)y) equal :

If cos x+ cos y = 1//3 , sin x + sin y=1//4 " then " cos (x+y)=

Prove geometrically that cos(x + y) = cos x cos y - sinx sin y and hence prove cos((pi)/(2) + x) = - sin x .

If sin x + sin y + sin z = 0 and cos x + cos y + cos z = 0 then prove that cot (x+y)/2 = cot z and cos (x-y)/2 = pm 1/2

Prove the following: cos(x+y)cos(x-y)=cos^2y-sin^2x

If cos x + cos y =(1)/(3) and sin x + sin y=(1)/(4) prove that tan ((x+y)/(2))=(3)/(4)

I : If cos x + cos y=1/3 , sin x+sin y=1//4 " then " cos (x+y)=7//25 II : If cos x + cos y=1//3 , sin x + sin y=1//4 " then " sin(x+y)=24//25