2010012809 | math4u.vsb.cz

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Project ID:

2010012809

Source Problem:

Accepted:

0

Clonable:

1

Easy:

0

Which of the following formulas expresses the area of a regular pentagon inscribed in a circle of radius

r

? (See the picture.)

\frac{5 r^{2} \sin 72^{\circ}}{2}

\frac{10 r^{2} \sin 72^{\circ}}{2}

\frac{5 r^{2} \sin 36^{\circ}}{2}

\frac{5 r \sin 36^{\circ}}{2}