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

Topic:
Area, Circle

## 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.