## anonymous one year ago IF triangle ABC and triangle PQR are similar triangles, find QR and PR QR= PR=

1. anonymous

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2. mathstudent55

Since the triangles are similar, corresponding sides have proportional lengths. First, you need to find a pair of sides, one side in triangle ABC and one side in triangle PQR, that are corresponding sides and that you know both lengths.

3. mathstudent55

Can you name such a pair of sides?

4. anonymous

IDK

5. mathstudent55

The way similar triangles are named tells you which sides are corresponding sides. |dw:1436546032187:dw|

6. mathstudent55

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7. anonymous

A/B=P/Q

8. mathstudent55

We have the lengths of both sides AB and PQ. |dw:1436546118626:dw|

9. anonymous

ok

10. mathstudent55

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11. anonymous

so how do i find QR AND PR

12. mathstudent55

We have the length of side BC, and we are looking for the length of side QR. We can set up a proportion: $$\dfrac{AB}{PQ} = \dfrac{BC}{QR}$$ Now we fill in all the lengths we know: $$\dfrac{15}{18} = \dfrac{25}{x}$$ We can cross multiply and solve for x. x is the length of side QR.

13. mathstudent55

$$15x = 25 \times 18$$ $$15x = 450$$ $$x = 30$$ Since x = QR, we now have QR = 30

14. mathstudent55

Now we do a similar proportion to find PR.

15. mathstudent55

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