# Lloyd Circles: Find d, r, C, A

- Author:
- Kathryn Lloyd, Duane Habecker, sciencereimer

## Class Work

In this lesson:
We use the pattern d, r, C, A
d =26 C = 26π
r =13 A = 169π
Notice in the pattern how we get from:
diameter to radius - diameter divided by 2 = radius
diameter to Circumference - diameter times π = Circumference
radius to diameter - radius times 2 = diameter
radius to Area - radius squared r² times π = Area

## Given the Figure:

Find d, r, C, A Leave your answer in terms of π. Use the slider to pick a different diameter for each problem.
1) d = C =
r = A =
2) d = C =
r = A =
3) d = C =
r = A =
4) d = C =
r = A =

## Given the Figure:

Find d, r, C, A Leave your answer in terms of π. Use the slider to pick a different radius for each problem.
5) d = C =
r = A =
6) d = C =
r = A =
7) d = C =
r = A =
8) d = C =
r = A =

## Given the Figure:

Find d, r, C, A Then use π = 3.14. Use the slider to pick a different diameter for each problem.
9) d = C = C =
r = A = A =
10) d = C = C =
r = A = A =

## Given the Figure:

Find d, r, C, A Then use π = 3.14. Use the slider to pick a different radius for each problem.
11) d = C = C =
r = A = A =
12) d = C = C =
r = A = A =

## Summary:

13) If you are given the diameter, how do you get the radius?
14) If you are given the diameter, how do you get the Circumference? What is the Formula? C =
15) If you are given the radius, how do you get the diameter?
16) If you are given the radius, how do you get the Area? What is the Formula? A =
NOTE: We can use the Formulas, but it's so much easier just to do d, r, C, A for every Circle problem.