" Let "(sin(theta-alpha))/(sin(theta-beta))=(a)/(b)" and "(cos(theta-alpha))/(cos(theta-beta))=(c)/(d)" then "(ac+bd)/(ad+bc)=

Let (theta-alpha)(sin(theta-alpha))/(sin(theta-beta))=(a)/(b) and (cos(theta-alpha))/(cos(theta-beta))=(c)/(d)then(ac+bd)/(ad+bc)= (a)cos (alpha-beta)(b)sin(alpha-beta)sin(alpha+beta)(d) none of these

Let (sin(theta-alpha))/("sin"(theta-beta))=a/b a n d(cos(theta-alpha))/("cos"(theta-beta))=c/d t h e n(a c+b d)/(a d+b c)=

Let (sin(theta-alpha))/("sin"(theta-beta))=a/b a n d(cos(theta-alpha))/("cos"(theta-beta))=c /d t h e n(a c+b d)/(a d+b c)= (a) cos(alpha-beta) (b) sin(alpha-beta) sin(alpha+beta) (d) none of these

Let (sin(theta-alpha))/("sin"(theta-beta))=a/b a n d(cos(theta-alpha))/("cos"(theta-beta))=c /d t h e n(a c+b d)/(a d+b c)= (a) cos(alpha-beta) (b) sin(alpha-beta) sin(alpha+beta) (d) none of these

Let (sin(theta-alpha))/("sin"(theta-beta))=a/b a n d(cos(theta-alpha))/("cos"(theta-beta))=c /d t h e n(a c+b d)/(a d+b c)= (a) cos(alpha-beta) (b) sin(alpha-beta) (c) sin(alpha+beta) (d) none of these

If (sin (theta- alpha))/(sin (theta- beta))=(x)/(y) and (cos (theta- alpha))/(cos(theta-beta))=(a)/(b) , then show that cos(alpha- beta)=(ax+by)/(bx+ay) .

s(theta-alpha)=a and cos(theta-beta)=b, then sin^(2)(alpha-beta)+2ab cos(alpha-beta)=

If sin(theta+alpha)=a,cos^(2)(theta+beta)=b, then sin(alpha-beta)=

If sin(theta+alpha)=a and sin(theta+beta)=b then cos2(alpha-beta)-4abcos(alpha-beta) is equal to