In the triangle ABC AC = BC = 20 inches and AB = 10 inches. Circle is inscribed in the triangle, what is the radius of the circle...see attached...#71

Results 1 to 8 of 8

- February 12th 2010, 01:22 PM #1

- Joined
- Jan 2010
- Posts
- 32

- February 12th 2010, 01:35 PM #2

- Joined
- Dec 2007
- From
- Ottawa, Canada
- Posts
- 3,102
- Thanks
- 68

- February 12th 2010, 01:40 PM #3

- Joined
- Jan 2010
- Posts
- 32

- February 12th 2010, 02:10 PM #4

- February 12th 2010, 02:16 PM #5

- Joined
- Jan 2010
- Posts
- 32

- February 12th 2010, 02:53 PM #6

- Joined
- Dec 2009
- Posts
- 3,120
- Thanks
- 1

- February 12th 2010, 04:18 PM #7

- Joined
- Dec 2007
- From
- Ottawa, Canada
- Posts
- 3,102
- Thanks
- 68

- February 13th 2010, 12:39 AM #8
1. You are dealing with 2 right triangles. (see attachment)

2. Grey triangle:

3. The right triangle at the top of the grey triangle:

4. Calculate h from 2. and plug in this term into the equation in 3. Solve for r.

__Spoiler__:

Second attempt: The 2 right triangles are similar. So use proportions:

First calculate h, then r using the proportion.