## anonymous 3 years ago Find the distance between the two points. Round to the nearest tenth if necessary. (2, 5) and (–1, –5)

1. anonymous

Make a triangle, Pythagorean theorem.

2. hartnn

or you could use this : Distance between points (x1,y1) and (x2,y2) is $$\huge d=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$$

3. anonymous

Distance formula is derived from Pythagoras' Theorem, I've found it's easier for students to remember the one formula than have to memorize another one.

4. anonymous

|dw:1349496154838:dw|

5. anonymous

It's easy enough to see what the lengths of the legs of the triangle are, then solve for the hypotenuse.

6. anonymous

1?

7. anonymous

Here are the choices: A. 1 B. 109 C. 10.4 D. 3

8. anonymous

9. anonymous

|dw:1349496503466:dw|

10. anonymous

1 doesn't seem very reasonable for points that far apart.

11. anonymous

10.4?

12. anonymous

That seems more reasonable, but how can you be sure? What if it wasn't a multiple choice question and you had to provide an exact value, not just one rounded to the tenths' place?

13. anonymous

oh i just counted how long the triangle's height was on the picture you drew, and i counted 10

14. anonymous

is it right?

15. anonymous

Ah, no. You have to use Pythagorean Theorem to find the hypotenuse of the right triangle. |dw:1349498042456:dw| Or perhaps you would have been better off using the distance formula hart provided..

16. anonymous

ok i'll try it....i'll tell you what i get

17. anonymous

oh wait

18. anonymous

how do i put (2,5) and (-1,-5) in that equation

19. anonymous

coordinates are (x,y) so substitute the coordinates' x's and y's

20. anonymous

109?

21. hartnn

yup, now don't forget to take aquare root.

22. hartnn

*square

23. anonymous

oh thank you! so it's 10.4 :D

24. hartnn

welcome :)

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