## Elementary Geometry for College Students (7th Edition)

$I = 108^{\circ}$
We can find the measure of the obtuse angles in the regular polygon with 5 sides: $I = \frac{(n-2)~180^{\circ}}{n}$ $I = \frac{(5-2)~180^{\circ}}{5}$ $I = \frac{(3)~180^{\circ}}{5}$ $I = 108^{\circ}$