Question

if a b and c are Interior angles of a triangle abc then cos (b+c2) is equal to a)sin a/2 b)-sin a/2 c)cos a/2 d)-cos a/2​

Answer 1

Answer:

If A, B and C are interior angles of a triangle ABC, then show that sin((B+C)/2)=cos(A/2). ∴cosA2=sin(B+C2)=L. H.