Problems of the Day1)

2)Challenge: Two triangles are similar. The ratio of the lengths of the corresponding sides is If the length of one side of the larger triangles is

40 feet, what is the length of the corresponding side of the smaller

triangles?

4

5

5-7: Indirect Measurement

Using proportions for problem solving

Vocabulary

Indirect Measurement

To use given corresponding sides of two or more polygons, to find the length of missing sides.

Steps in Solving

To find the missing lengths of two similar polygons…

I. Write a proportion using the given corresponding lengths and missing length.

• Be sure to place the corresponding lengths, in thecorresponding position in the proportion.

II. Use cross multiplication, or other strategies to solve the proportion.

Problems/ Examples of

A. The two triangles below are similar. Find the value of x. Set up an proportion and solve.

B. The two triangles below are similar. Find the values of ‘a’ and ‘b’. Set-up proportions to solve.

C. A person with a height of 2 meters stands near a tree. The tree casts a shadow that is 30 meters long and the person has a shadow that is 3 meters long. What is the height of tree? (Drawing a rough sketch helps is solving).

D. A 30 ft. building casts a shadow that is 75 ft. long. A nearby tree casts a shadow that is 35 ft. long. How tall is the tree?

Now Try These…