First, area of large circle(A1)= pie×R^2
=3.14×(3+4)^2=3.14×49=154 sq. cm
area of small circle (A2) pie× r^2
=3.14×3^2=28.27 sq.cm
now
area of shaded region= (A1-A2)/3
=(154-28.27)/3
=125.73/3
=41.91 sq. cm
