Area of a Circle Donut From Outer Radius and Area to Inner Radius (Equation) (Level 1)

This math topic focuses on calculating the inner radius of a circle donut, using given values for the outer radius and the total area of the donut. Each problem provides a different combination of outer radius and area, and students are asked to determine the matching inner radius from multiple choice options. This involves understanding the geometric relationships within circular figures, specifically applying the formulas for the areas of circles to find unknown dimensions within composite shapes like donuts. These problems fall under an introductory unit on the area of circles, sectors, and donuts in geometry.

Work on practice problems directly here, or download the printable pdf worksheet to practice offline.

Area of a Circle Donut From Outer Radius and Area to Inner Radius (Equation) Worksheet

Math worksheet on 'Area of a Circle Donut From Outer Radius and Area to Inner Radius (Equation) (Level 1)'. Part of a broader unit on 'Geometry - Circle Area, Sectors and Donuts - Intro' Learn online: app.mobius.academy/math/units/geometry_circles_sector_donut_area_logic_intro/

1

Find the inner radius of the donut with an area of 9 π and an outer radius of 5

a

1

b

3

c

6

d

4

e

7

f

8

2

Find the inner radius of the donut with an area of 12 π and an outer radius of 4

a

4

b

8

c

10

d

6

e

1

f

2

3

Find the inner radius of the donut with an area of 33 π and an outer radius of 7

a

13

b

2

c

1

d

4

e

5

f

12

4

Find the inner radius of the donut with an area of 16 π and an outer radius of 5

a

11

b

9

c

5

d

10

e

2

f

3

5

Find the inner radius of the donut with an area of 15 π and an outer radius of 4

a

1

b

5

c

3

d

7

e

8

f

6

6

Find the inner radius of the donut with an area of 80 π and an outer radius of 9

a

1

b

10

c

9

d

6

e

2

f

7

7

Find the inner radius of the donut with an area of 8 π and an outer radius of 3

a

2

b

1

c

4

d

5

e

6

f

9