Worksheet Chapter 9: Basic Polygons

1. A polygon has 14 diagonals. Using the diagonal formula, find the number of sides this polygon has and name the polygon.

2. Which quadrilateral has all sides equal in length and diagonals that bisect each other at right angles?

3. The interior angles of a quadrilateral are given as x°, (x + 20)°, 2x°, and 80°. Calculate the value of x.

4. An exterior angle of a triangle is 130°. If one of the opposite interior angles is twice the other opposite interior angle, find the measure of both interior angles.

5. In an isosceles triangle, the vertex angle measures 50°. Find the value of each base angle.

6. True or False: The sum of the interior angles of a triangle is always 180 degrees.

7. Fill in the blank: A polygon with 8 sides is called an ________.

8. True or False: A kite has 2 lines of symmetry.

9. In a parallelogram ABCD, angle A = (3x - 10)° and angle C (opposite angle to A) = (x + 50)°. Calculate the value of x and find all 4 interior angles of the parallelogram.

10. Calculate the number of diagonals in a polygon with 10 sides (decagon).