Home > GC > Chapter 9 > Lesson 9.1.1 > Problem9-9

9-9.

Find the area of a regular decagon with perimeter $100$ units. Show all work.

Find the length of each side, then find the central angle.

Use the tangent ratio to find the height of the triangle, then find the area of the triangle.

$h=\frac{5}{\tan{18°}}$

Use the area of the triangle to find the total area of the shape.