[tex]area \: of \: circle \: a1 = \pi {r}^{2} = \pi \times {21}^{2} = \\ 441\pi sq \: \: .in \\ area \: of \: triangle \: a2 = \frac{1}{2} bh = \frac{1}{2} \times 20 \times 39 \\ = 390 \: sq.in \\ now \: area \: of \: shaded \: region = a1 - a2 \\ = 441\pi - 390 \\ = 995.44 \: sq.in[/tex]
