Answer:
Step-by-step explanation:
all the three sides of a triangle are equal.
length of perpendicular from center on the side=[tex]h=\sqrt{21^2-(\frac{21}{2})^2} =\frac{21}{2}\sqrt{3} \\area ~of~shape=6 \times \frac{1}{2} \times 21 \times \frac{21}{2}\sqrt{3} \\=\frac{1321}{2}\sqrt{3} ~sq. ~ft.[/tex]
