## ayyookyndall one year ago Help

1. MeowLover17

Think of the diameter as a line, solve for the midpoint of that line to find the center.

2. MeowLover17

And the radius is basically the length from the midpoint to the end of the circle, in this case being one of the other coordinates.

3. MeowLover17

The formula would be

4. MeowLover17
5. MeowLover17

Good luck thats all the information i can give.

6. jim_thompson5910

where are you stuck? are you stuck on the formula given on the page MeowLover17 gave you?

7. ayyookyndall

Yes, putting it in.

8. jim_thompson5910

P(-10,-2) and Q(4,6) the x coordinates of each point are -10 and 4 add them up: -10+4 = -6 divide the result by 2: -6/2 = -3 so the x coordinate of the midpoint is x = -3 Do the same for the y coordinates to get the y coordinate of the midpoint

9. jim_thompson5910

very good

10. ayyookyndall

Thats it for Part A?

11. jim_thompson5910

so that's effectively what this formula $\LARGE (x_m, y_m) = \left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)$ is saying "add up the corresponding coordinates and divide by 2 to get the midpoint "

12. ayyookyndall

Okay, got it. :-)

13. jim_thompson5910

yes the midpoint of P and Q is the center because P and Q lie on the same diameter |dw:1432945083421:dw|

14. jim_thompson5910

The radius can be found in 2 ways a) find the distance from the midpoint, ie center, to P or Q (pick one) b) find the distance from P to Q, then divide by 2

15. ayyookyndall

Which one will be easier?

16. jim_thompson5910

they're about equal in difficulty since you need to use the distance formula either way

17. ayyookyndall

I guess lets do A

18. jim_thompson5910

alright, so you can find the distance from the midpoint to P OR find the distance from the midpoint to Q

19. ayyookyndall

Find the distance from the midpoint to P

20. jim_thompson5910

use the distance formula $\large d = \sqrt{\left(x_{2}-x_{1}\right)^2+\left(y_{2}-y_{1}\right)^2}$ to find the distance from the midpoint (-3,2) to point P(-10,-2)

21. jim_thompson5910

(x1,y1) = (-3,2) (x2,y2) = (-10,-2)

22. jim_thompson5910

good, now take the square root of that

23. jim_thompson5910

so the exact distance is $\Large \sqrt{65}$ notice how it says "If your answer is not an integer, express it in radical form"

24. jim_thompson5910

"radical" is math term for "square root, cube root, fourth root, etc"

25. ayyookyndall

Did I get it right?

26. ayyookyndall

Can't I say 8.06

27. jim_thompson5910

8.06 is the approximate distance, but they want the exact form

28. jim_thompson5910

29. ayyookyndall

Are we done or is there more?

30. ybarrap

|dw:1432944559846:dw|

31. jim_thompson5910

they just want the radius, so we're done

32. jim_thompson5910

|dw:1432945973861:dw|

33. jim_thompson5910

an integer is a whole number (not just any number)

34. jim_thompson5910

example of integers: -3, -22, 5, 8, 0, 157 example of nonintegers: 2.7, 8.5, $$\large \sqrt{15}$$, $$\large \pi$$

35. ayyookyndall

Oh, I understand. Thank you! ;-)

36. jim_thompson5910

np