1. Using Similar Figures to Solve Problems

2. There are a variety of problems that can be solved with similar triangles. To make things easier use or draw a picture to help you find the congruent angles and corresponding edges.

3. Example #1: Using Shadows to find the height of things. What is the height of the clock tower that casts a 43.75 foot shadow at the same time a 12 foot light pole casts a 15 foot shadow? x 12 43.7515 The clock tower is 35 feet tall.

4. Example 2: More shadow problems without a picture… Hank is 6 foot tall. He casts a shadow that is five feet long at the same time a nearby tree casts a 35 foot shadow. How tall is the tree? 6 x 535 The tree is 42 feet tall.

5. Example #3: Finding the width of a river You need to know the width of the river. You spot two trees across the river. You find the distance between those trees is 160 feet. You set up two flags parallel to the trees on your side of the river that are 8 feet apart. You stand so that you see both flags and trees in your line of vision. You are 10 feet away from the flag on the left. How wide is the river? 160 8 10 x The river is 190 feet wide.

6. Example #4: The width of the river again… You can also find similar triangles when you can line up one object on the far side of the river with two objects on the near side. A B 15m 12 m 48 m x The river is 60 feet wide.

7. Example #5: Similar figures that are not triangles… The editor of the school newspaper must reduce the size of a graph to fit in one column. The original graph is 10 inches in width by 6 inches in height. The column width needs to be 2.5 inches. What would the height be? 10 2.5 6 x The height would be 1.5 inches.