## zhane2015 2 years ago A triangle has side lengths of 12 cm, 15 cm, and 20 cm. Classify it as acute, obtuse, or right. (1 point) acute obtuse right There is not enough information.

1. zhane2015

I wanna choose Right...

2. Directrix

By the converse of the Pythagorean Theorem, if 20^2 = 15^2 + 12^2, then "right" is correct. Check the arithmetic and let us know. @zhane2015

3. Directrix

What is 20*20?

4. zhane2015

400

5. Directrix

Good. What is 15 times 15?

6. Directrix

You can enter "15 times 15" in the Google search box and get the product. @zhane2015

7. Directrix

> I wanna choose Right... @zhane2015 Suggest you not choose until the arithmetic is done.

8. zhane2015

225

9. Directrix

Okay. I'll do 12 times 12 to get 144.

10. Directrix

12 cm, 15 cm, and 20 cm. ------------------------ Question: Is 12^2 + 15^2 = 20^2 That is, is 144 + 225 = 400? Yes or No?

11. zhane2015

no

12. Directrix

Okay. Therefore, the triangle is NOT Right. That leaves Obtuse and Acute. Check out this attachment below: (comes from http://jwilson.coe.uga.edu/emt668/emat6680.folders/brooks/6690stuff/righttriangle/pythagconv.html )

13. zhane2015

OMG you're the Best!

14. Directrix

Let's test for acute. Is 400 < 225 + 144 [ Is 20^2 < 12^2 +15^2 ] Yes or No? @zhane2015

15. zhane2015

no

16. zhane2015

So it's obtuse

17. Directrix

Correct.

18. zhane2015

Thank You so much I really appreciate it

19. Directrix

Glad to help. Learn that theorem on the chart and you'll get all this type problem correct.