" (a) "tan((A+B)/(2))+tan((A-B)/(2))=(2sin A)/(cos A+cos B)

tan ((A + B) / (2)) + tan ((AB) / (2)) = (2sin A) / (cos A + cos B)

"Prove that" tan (A+B) - tan (A - B) = (sin2 B)/(cos^(2)B - sin^(2) A).

If (x)/(y)=(cos A)/(cos B) where A!=B ,then (a) tan(A+B)/(2)=(x tan A+y tan B)/(x+y) (b) tan(A-B)/(2)=(x tan A-y tan B)/(x+y) (c) (sin(A+B))/(sin(A-B))=(y sin A+x sin B)/(y sin A-x sin B) (d) (x cos B-y cos A)/(xcosB+ ycosA)=0

Prove that :(tan(A+B))/("cot"(A-B))=(sin^2A-sin^2B)/(cos^2A-sin^2B)

Prove the following identities: tan^(2)A-tan^(2)B=(cos^(2)B-cos^(2)A)/(cos^(2)B cos^(2)A)=(sin^(2)A-sin^(2)B)/(cos^(2)A cos^(2)B)(sin A-sin B)/(cos A+cos B)+(cos A-cos B)/(sin A+sin B)=0

By using above basic addition/ subtraction formulae, prove that (i) tan (A+B)=(tan A+tan B)/(1-tan A tan B) , (ii) tan (A-B)=(tan A-tanB)/(1+tan A tan B) (iii) sin2theta=2sintheta costheta , (iv) cos2theta=cos^(2)theta=1-2sin^(2)theta=2cos^(2)theta-1 (v) tan 2theta=(2 tan theta)/(1-tan^(2) theta)

By using above basic addition/ subtraction formulae, prove that (i) tan (A+B)=(tan A+tan B)/(1-tan A tan B) , (ii) tan (A-B)=(tan A-tanB)/(1+tan A tan B) (iii) sin2theta=2sintheta costheta , (iv) cos2theta=cos^(2)theta=1-2sin^(2)theta=2cos^(2)theta-1 (v) tan 2theta=(2 tan theta)/(1-tan^(2) theta)

By using above basic addition/ subtraction formulae, prove that (i) tan (A+B)=(tan A+tan B)/(1-tan A tan B) , (ii) tan (A-B)=(tan A-tanB)/(1+tan A tan B) (iii) sin2theta=2sintheta costheta , (iv) cos2theta=cos^(2)theta=1-2sin^(2)theta=2cos^(2)theta-1 (v) tan 2theta=(2 tan theta)/(1-tan^(2) theta)

tan A ++ tan B + tan C- (sin (A + B + C)) / (cos A cos B cos C) =

Prove that tan^2A - tan^2B = (sin(A+B).sin(A-B))/(cos^2A.cos^2B