`cosA=(1-tan^2(A/2))/(1+tan^2(A/2)`

If A=30^(@) , verify that (i) sin2A=(2tanA)/(1+tan^(2)A) (ii) cos2A=(1-tan^(2)A)/(1+tan^(2)A) (iii) tan2A=(2tanA)/(1-tan^(2)A)

If (A)/(2) and A are not an odd multiple of (pi)/(2) then tan A= (2tan A)/(1-tan^(2)A) (2tan A)/(1+tan^(2)A) (2tan (A/2))/(1-tan^(2)(A/2))

cos ^ (2) A-sin ^ (2) A = (1-tan ^ (2) A) / (1 + tan ^ (2) A)

The value of (1+tan^2A)/(1-tan^2A) is

Prove that: tan(A+B)tan(A-B)=(tan^(2)A-tan^(2)B)/(1-tan^(2)A tan^(2)B)

prove that- (sinA+sin(A/2))/(1+cosA+cos(A/2))= tan(A/2)

Prove that (1+tan^(2)A)/(1+cot^(2)A)=((1-tan A)/(1-cot A))^(2)=tan^(2)A

Show that : ((1+tan^(2)A)/(1+cot^(2)A))=((1-tan A)/(1-cot A))^(2)=tan^(2)A

((1+tan^(2)A)/(1+cot^(2)A))=((1-tan A)/(1-cot A))^(2)=tan^(2)A

(1+ (tan A) / (2)) / (1- (tan A) / (2)) = sec A + tan A