# Similar triangle

1. May 15, 2012

### xzibition8612

1. The problem statement, all variables and given/known data

see attachment

2. Relevant equations

3. The attempt at a solution

No idea how to do this. Tried extending the 10 thus getting a big triangle of (10+x)^2+y^2=400. But then again no idea what x and y is. This is wrong. Any help would be appreciated.

#### Attached Files:

• ###### triangle.jpg
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2. May 15, 2012

### Staff: Mentor

If you understand what the term 'similar triangles' means, it should be obvious that the two triangles in your sketch are NOT similar.

If the problems isn't merely to determine whether the triagles are similar, please provide a complete problem statement.

3. May 15, 2012

### phinds

so what is the question?

EDIT: OOPS --- Mark beat me to it.

4. May 16, 2012

### xzibition8612

The question is how do i find the length of the unknown side (???). The figure is all I'm given. Any idea? I thought about extending the bottom (length 10) and thus making the entire triangle a right triangle and using that with 5-12 relationship of the slope of the unknown side, but not sure how to do this. any law of sin or cos that's applicable hhere?

5. May 16, 2012

### phinds

I cannot see that the ??? attaches to any particular line, but there are TWO lines that it MIGHT attach to.

EDIT: Oh, I see. It's really trivial. Do you know the pathagorean theorem? Starting hint --- extend the 5/12 triangle and you'll have a single right triangle that can be solved for it's sides and then go from there.

6. May 16, 2012

### xzibition8612

i figured it out. the length is 10-13.9-20. I used the law of cosines.

7. May 21, 2012

### Staff: Mentor

That doesn't make any sense. The length has to be positive, and what you show is a negative number.

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