[" 12.If "(cos alpha)/(cos beta)=m" and "(cos alpha)/(sin beta)=n" ,show that "(m^(2)+n^(2))],[cos^(2)beta=n^(2)" .[CBSE "2012]]

If n=(cos alpha)/(cos beta),m=(sin alpha)/(sin beta) then (m^(2)-n^(2))sin^(2)beta is

(cos alpha + cos beta) ^ (2) + (sin alpha + sin beta) ^ (2) =

If cos alpha+cos beta=0=sin alpha+sin beta then cos2 alpha+cos2 beta=

If sin alpha+sin beta=a and cos alpha+cos beta=b show that sin(alpha+beta)=(2ab)/(alpha^(2)+beta^(2))

If (cos^4 alpha)/(cos^2beta)+(sin^4alpha)/(sin^2beta)=1 ,then prove that (cos^4beta)/(cos^2alpha)+(sin^4beta)/(sin^2alpha)=1

Prove that (cos2 alpha-cos 2 beta)/(sin2 alpha+sin2 beta)=tan(beta-alpha)

If (cos^4 alpha)/(cos^2 beta)+ (sin^4 alpha)/(sin^2 beta) =1 , prove that : (cos^4 beta)/(cos^2 alpha)+ (sin^4 beta)/ (sin^2 alpha) =1 .

If "tan" alpha= n tan beta and sin alpha =m sin beta prove that : cos^(2)alpha=(m^(2)-1)/(n^(2)-1)