If `cos(alpha-beta)=3sin(alpha+beta),t h e n 1/(1-3sin2alpha)+1/(1-3sin2beta)=` (a)`1/2` (b) `(-1)/2` (c) `1/4` (d) `(-1)/4`

If cos(alpha-beta)=3sin(alpha+beta),t h e n1/(1-3sin2alpha)+1/(1-3sin2beta)= 1/2 (b) (-1)/2 (c) 1/4 (d) (-1)/4

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

If cos alpha+ cos beta =1/3 and sin alpha+sin beta=1/4 prove that cos[(alpha-beta)/2] =+-(5/24)

If (tan(alpha+beta-gamma))/("tan"(alpha-beta+gamma))=(tangamma)/(tanbeta),(beta!=gamma) then sin2alpha+sin2beta+sin2gamma= (a) 0 (b) 1 (c) 2 (d) 1/2

If 3cosalpha=2cos(alpha-2beta), then tan(alpha-beta) tanbeta= (A) 5 (B) -5 (C) 1/5 (D) -1/5

If : sin (alpha + beta)=1 and sin (alpha-beta)=(1)/(2), "then" : tan (alpha+2beta)*tan(2alpha+beta)=

If tan beta = 3 tan alpha, prove that tan (alpha + beta) = (2sin 2beta)/(1+cos 2beta)

Prove that: cos2alpha\ cos2beta+sin^2(alpha-beta)-sin^2(alpha+beta)=cos2(alpha+beta) .

cos 2 alpha =(3 cos 2 beta -1)/( 3-cos 2 beta), then tan alpha=

If the eccentric angles of the extremities of a focal chord of an ellipse x^2/a^2 + y^2/b^2 = 1 are alpha and beta , then (A) e = (cos alpha + cos beta)/(cos (alpha + beta)) (B) e= (sin alpha + sin beta)/(sin(alpha + beta)) (C) cos((alpha-beta)/(2)) = e cos ((alpha + beta)/(2)) (D) tan alpha/2.tan beta/2 = (e-1)/(e+1)