Level:
Project ID:
2000005908
Accepted:
0
Clonable:
0
Easy:
1
Which of the following formulas gives the area of a regular nonagon inscribed in a circle with radius \(r\)? (See the picture.)
\(\frac{9r^2\sin{40^{\circ}}}{2}\)
\({9r^2\sin{40^{\circ}}}\)
\(\frac{9r^2\cos{40^{\circ}}}{2}\)
\(\frac{9r^2\sin{20^{\circ}}}{2}\)