In geometry, an arc is one of the parts of the circumference of a circle. Or, a regular pentagon circumscribed about a circle. Each central angle is equal to 360 / 5 = 72 … Hi Elaine. 4. The inner shape is called "inscribed," and the outer shape is called "circumscribed." The Trigonometric Functions. curiosity; finding an upper bound for n-regular polygons inscribed in n-1 sided polygons, both inscribed within the same circumcircle 2015/02/01 03:18 Male/Under 20 years old/Elementary school/ Junior high-school student/Very/ Purpose of use Regular polygons inscribed to a circle area 2015/01/11 03:00 Male/40 years old level/A retired people/Very/ In this case, this inscribed angle (