Lesson 3: Midpoint - Midpoint of Polygons: Triangle Examples

   Multimedia

A video describing finding the midpoint of a triangle is provided.


EXAMPLE 3

Find the midpoint of the equilateral triangle shown.



Solution


Step 1: Find the midpoint of each side.

Midpoint of side = 5 cm ÷ 2
= 2.5 cm



Step 2: Connect the midpoints to the opposite vertices, using a ruler.



The midpoint of the triangle is where the three lines intersect.

EXAMPLE 4

A garden gnome is to be placed in the middle of a triangular shaped garden. The side lengths of the garden are 1.75 m, 2 m, and 2.5 m. Find the middle of the garden.



Solution


Step 1: Find the midpoint of each side.

Midpoint of side 1 = 2 ÷ 2
Midpoint of length = 1 m
 
Midpoint of side 2 = 1.75 ÷ 2
Midpoint of length = 0.875 m
 
Midpoint of side 3 = 2.5 ÷ 2
Midpoint of length = 1.25 m



Step 2: Connect the midpoints to the opposite vertices, using a ruler.

Where the lines intersect is the midpoint.



The center of the garden is where the three lines intersect.

   Points to Ponder

In example 4, a string line would be used to join the midpoints of the sides to the opposite vertices. This technique is used for construction projects like laying tile patterns on floors, or finding the middle of a deck.



Now, it is your turn! Complete the questions in your Chapter 6, Lesson 3 Practice Makes Perfect that refer to Midpoint of Polygons.



2014 © Alberta Distance Learning Centre