Grade 4 - Progress in Mathematics

Add the number of lights around the figure.

5 
 4 
 3  12

Visualize the facts of the

problem as you reread it.

Facts: 1 light—at each vertex

1 light—every half foot along

each 2-foot-long side

Question: How many lights will the sign have?

The Hobby Hut sign is a triangle.

The owner wants a light at each vertex

and every half foot along each side.

Each side is 2 ft long. How many

lights will the sign have?

Problem-Solving Strategy:

Use a Drawing or Model

11-8

1 light at each vertex 3  1  3

3 lights along each side 3  3  9

The total number of lights 3 
 9  12

The sign will have 12 lights.

?

?

2 ft

1 ft

ft^12

Since each side is 2 ft long,

the sign is an equilateral triangle.

Draw an equilateral triangle.

Use marks for each light.

Multiply to find the number

of lights:

at each vertex 3  1 

along each side 3  3 

Then add to find the total.

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