Letter To Family - Geometry Of Plane Figuers printable pdf download

Letter To Family - Geometry Of Plane Figuers

Chapter 9 9

What We’re Learning

Vocabulary

complementary angles Two angles

During the next few weeks, our math class

for which the sum of the angle measures

will be learning about geometry of plane

is 90°.

figures. We will be studying lines, angles,

supplementary angles Two angles

circles, and polygons.

for which the sum of the angle measures

You can expect to see work that provides

is 180°.

practice in finding sums of angles in

polygons. You may wish to use this

information as a guide to help your child.

Guiding Your Child

Using Angle Sums

The sum of the angles of a triangle is 180°. You can use this information

about triangles to find the sum of the angles of other regular polygons.

1. Draw all the diagonals from one vertex of the figure.

110

2. Count the number of triangles.

3. Multiply the number of triangles in the figure by 180° to find the sum of the angles in the figure.

parallelogram

pentagon

hexagon

octagon

4 sides, 2 triangles

5 sides, 3 triangles

6 sides, 4 triangles

8 sides, 6 triangles

sum of angles = 360°

sum of angles = 540°

sum of angles = 720°

sum of angles = 1,080°

During this chapter, students will need to continue practicing

addition, subtraction, multiplication, and division skills.

Sincerely,

Your child’s teacher

Letter To Family - Geometry Of Plane Figuers