Answer:
63.3 square feet
Step-by-step explanation:
Let a = 20 ft, B = 15 ft, c = 9ft
[tex] s=\frac{a+b+c}{2} [/tex]
[tex] s=\frac{20+15+9}{2} [/tex]
[tex] s=\frac{44}{2} [/tex]
[tex] s=22\: ft[/tex]
[tex]Area \: of \:\triangle = \sqrt{s(s - a)(s - b)(s - c)} \\ \\ = \sqrt{22(22 - 20)(22 - 15)(22 - 9)} \\ \\= \sqrt{22 \times 2 \times 7 \times 13} \\ \\= \sqrt{44 \times 91} \\ \\ = \sqrt{4,004} \\ \\ = 63.2771681 \\ \\ \approx 63.3 \: {ft}^{2} [/tex]
