1. Find the circumference of a circle with a radius of 20 m? 2.Find the area of a circle with a diameter of 10 m.?

3.Find the radius of a circle with a circumference of 15π m?

The shape of polygon is Nonagon.

Step-by-step explanation:

We need to find name of polygon whose number of vertex is one more than an octagon.

The number of vertex of octagon is 8 because total 8 side of octagon.

The number of vertex of required polygon is 1 more than 8

Thus, The number of vertex of required polygon is 8+1 = 9

The number of side of polygon is 2 fewer than a hendecagon.

The side of hendecagon = 11

The number of side of required polygon is 2 fewer than 11

Thus, The number of side of required polygon is 11-2 = 9

The number of side required polygon is 9 and number of vertex of polygon is 9.

Thus, It must be Nonagon because Nonagon has 9 sides and 9 vertex.