Question

bCosB+cCosC=acos(B-C)​

Answer 1

Step-by-step explanation:

cosc + cosD=2cos(c+d)/2×

cos(c-d)/2

=let 2=a,c=b,d=c

a cos (b+c)/a×sin( b-c)/a

multiply and divide by -cos

=acos( B-C)