class 11

Math

Algebra

Sequences and Series

If the angle $A,BandC$of a triangle are in an arithmetic propression and if $a,bandc$denote the lengths of the sides opposite to $A,BandC$respectively, then the value of the expression $ca sin2C+ac sin2A$is$21 $ (b) $23 $ (c) $1$ (d) $3 $