### Home > GC > Chapter 12 > Lesson 12.2.3 > Problem 12-77

12-77.

Find the area of the shaded region of the regular pentagon at right. Show all work. Homework Help ✎

Label the shaded region as ∠ABC.

Divide ΔABC into two triangles. Use a trigonometric ratio to solve for AD.

Find the area of ΔABC now that you know the lengths of both its base and height.

6.2 units²