1. Before: April 4, 2016 Are triangle KRA and triangle FLN similar?
How do you know?
A flagpole casts a shadow 18 ft. long. At the same time, Rachael casts a shadow that is 4 ft. long. If Rachel is 5 ft. tall, what is the height of the flagpole?
Are the triangles similar? If so, what is the
similarity statement.

2. During: Similarity in Right Triangles
To find and use relationships in similar right triangles.

3. When you draw the altitude to the hypotenuse of a right triangle, you form three pairs of right triangles.
Theorem 7 – 3
Theorem
If…
Then…
The altitude to the hypotenuse of a right triangle divides the triangle into two triangles that are similar to the original triangle and to each other.
Triangle ABC is a right triangle with right <ACB, and CD is the altitude to the hypotenuse…

4. Problem 1: Identifying Similar Triangles “I Do”
What similarity statement can you write relating the three triangles in the diagram?

5. Problem 1: Identifying Similar Triangles “We Do”
What similarity statement can you write relating the three triangles in the diagram?

6. Problem 1: Identifying Similar Triangles “You Do”
What similarity statement can you write relating the three triangles in the diagram?

7. Geometric Mean

8. Problem 2: Finding the Geometric Mean “I Do”
What is the geometric mean of 6 and 15?

9. Problem 2: Finding the Geometric Mean “We Do”
What is the geometric mean of 4 and 18?

10. Problem 2: Finding the Geometric Mean “You Do”
What is the geometric mean of 5 and 12?

11. Corollary 1 to 7-3 Corollary If… Then…
The length of the altitude to the hypotenuse of a right triangle is the geometric mean of the lengths of the segments of the hypotenuse.
CD = 𝐴𝐷 ·𝐷𝐵

12. Corollary 2 to 7-3 Corollary If… Then… AC = 𝐴𝐵 ·𝐴𝐷
The altitude to the hypotenuse of a right triangle separates the hypotenuse so that the length of each leg of the triangle is the geometric mean of the length of the hypotenuse and the length of the segment of the hypotenuse adjacent to the leg.
AC = 𝐴𝐵 ·𝐴𝐷

13. Problem 3: Using the Corollaries “I Do”
What are the values of x and y?

14. Problem 3: Using the Corollaries “We Do”
What are the values of x and y?

15. Problem 3: Using the Corollaries “You Do”
What are the values of x and y?

16. Problem 4: Finding a Distance “I Do”
You are preparing for a robotics competition using the setup shown here. Points A, B, and C are located so that AB = 20 in., and AB is perpendicular to BC. Point D is located on AC so that BD is perpendicular to AC and DC = 9in. You program the robot to move from A to D and to pick up the plastic bottle at D. How far does the robot travel from A to D?

17. Problem 4: Finding a Distance “We Do”
From point D, the robot must turn right and move to point B to put the bottle in the recycling bin. How far does the robot travel from D to B?

18. Problem 4: Finding a Distance “You Do”
Maggie has a kite with the dimensions shown below. What is the width of the kite?

19. After: Lesson Check Find the geometric mean of each pair of numbers.
4 and 9
4 and 12
Identify the following in triangle RST.
The hypotenuse
The segments of the hypotenuse
The segments of the hypotenuse adjacent to leg ST

20. Homework:
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