If `cos^(-1)x/2+cos^(-1)y/3=theta` , then `9x^2-12 x ycostheta+4y^2` is equal to (a) 36 (b) `-36\ sin\ ^2theta` (c) `36\ sin\ ^2theta` (d) `36\ cos\ ^2theta`

If cos^(-1)(x/2)+cos^(-1)(y/3) = theta , prove that 9x^2- 12xycostheta+ 4y^2= 36 sin^(2)theta

If "cos"^(-1) x/(2)+"cos"^(-1) y/(3)=theta , then prove that 9x^(2)-12xy " cos "theta+4y^(2)=36" sin "^(2)theta

If cos^(-1)x/3+cos^(-1)y/2=theta/2 , then 4x^2-12 x ycostheta/2+9y^2= (a) 36 (b) 36-36costheta (c) 18-18costheta (d) 18+18costheta

If cos^(-1)(x)/(2)+cos^(-1)(y)/(3)=theta then the maximum of 9x^(2)-12xy costheta + 4y^(2) is

If cos ^(-1) ""(x)/(2) + cos ^(-1) "" (y)/(3) = theta, then prove that 9x ^(2) - 12 xy cos theta + 4y ^(2) = 36 sin ^(2) theta

If cos^(-1) (x/2) + cos^(-1) (y/3) =alpha then prove that 9x^2-12xycosalpha+4y^2=36sin^2alpha .

If cos^(-1)""x/a+cos^(-1)""y/b=theta , Prove that x^(2)/a^(2)-(2xy)/(ab)costheta+y^(2)/b^(2)=sin^(2)theta .

If cos^(-1)((x)/(3))+cos^(-1)((y)/(2))=(theta)/(2) , then the value of 4x^(2)-12xy cos((theta)/(2))+9y^(2) is equal to :

If sin^(-1)x=theta+betaa n dsin^(-1)y=theta-beta, then 1+x y is equal to sin^2theta+sin^2beta (b) sin^2theta+cos^2beta cos^2theta+cos^2theta (d) cos^2theta+sin^2beta

Prove that cos^6 theta+ sin^6 theta= 1-3sin^2 theta cos^2 theta