" 15.Show that "(b-c)^(2)cos^(2)(A)/(2)+(b+c)^(2)sin^(2)(A)/(2)=a^(2)

For DeltaABC prove that, (a-b)^(2)cos^(2)""(C)/(2)+(a+b)^(2)sin^(2)""(C)/(2)=c^(2)

Show that, in a triangle ABC. a^(2) = (b - c)^(2) cos^(2) (A/2) + (b + c)^(2) sin^(2) (A/2) .

In any triangle ABC,show that: 2a cos((B)/(2))cos((C)/(2))=(a+b+c)sin((A)/(2))

If A+B+C=180^(@), then prove that cos^(2)(A)/(2)+cos^(2)(B)/(2)+cos^(2)(C)/(2)=2(1+sin(A)/(2)sin(B)/(2)sin(C)/(2))

If A+B+C = pi show that cos^2 (A/2)-cos^2 (B/2)-cos^2 (C/2)=-2sin(A/2)cos(B/2)cos(C/2)

Show that (a sin (B-C))/( b^(2) - c^(2)) - ( b sin (C-A))/( c^(2) - a^(2)) - ( c sin ( A- B))/( a^(2) -b^(2))

If the sides a,b and C of o+ABC are in A.P.,prove that 2sin(A)/(2)sin(C)/(2)=sin(B)/(2)a cos^(2)(C)/(2)+cos^(2)(A)/(2)=(3b)/(2)

(cos^(2)((B-C)/(2)))/((b+c)^(2))+(sin^(2)((B-C)/(2)))/((b-c)^(2))=(1)/(a^(2))

In any triangle ABC, show that : 2a cos (B/2) cos (C/2) = (a+b+c) sin (A/2)

a (cos B + cos C) = 2 (b + c) sin ^ (2) ((A) / (2))