Home
Grade 1Grade 2Grade 3Grade 4Grade 5Grade 6Grade 7Grade 8Grade 9Grade 10Math Themes
Explorers (Grades 1-3)Explorers Elite (1-3)Navigators (Grades 4-6)Navigators Elite (4-6)Challengers (Grades 7-9)Challengers Elite (7-9)Schedule an Evaluation
Mobius MethodFlexible ClassesCompanySupport
Pricing
Ctrl+k
Sign InJoin

Geometry - Circle Area, Sectors and Donuts - Intro

50 Topics, 5 Skills

Part Circle - Full Area and Fraction to Part Area (Decimal)

Topic 1

Part Circle - Full Area and Fraction to Part Area (Pi Value)

Topic 2

Part Circle - Part Area and Fraction to Full Area (Decimal)

Topic 3

Part Circle - Part Area and Fraction to Full Area (Pi Value)

Topic 4

Circle Sector From Fraction to Area (Equation)

Topic 5

Circle Sector From Fraction to Area (Equation)

Topic 6

Circle Sector From Fraction to Area (Closest Integer)

Topic 7

Circle Sector From Angle to Area (Equation)

Topic 8

Circle Sector From Angle to Area (Equation)

Topic 9

Circle Sector From Angle to Area (Closest Integer)

Topic 10

Circle Donut From Both Radii to Area (Equation)

Topic 11

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

Topic 12

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

Topic 13

Circle Sector From Arc Length to Area (Equation)

Topic 14

Circle Sector From Arc Length to Area (Equation)

Topic 15

Circle Sector From Arc Length to Area (Closest Integer)

Topic 16

Circle Sector From Area to Fraction (Equation)

Topic 17

Circle Sector From Area to Fraction (Equation)

Topic 18

Circle Sector From Area to Fraction (Closest Integer)

Topic 19

Circle Sector From Area to Angle (Equation)

Topic 20

Circle Sector From Area to Angle (Equation)

Topic 21

Circle Sector From Area to Angle (Closest Integer)

Topic 22

Circle Sector From Area to Arc Length (Equation)

Topic 23

Circle Sector From Area to Arc Length (Equation)

Topic 24

Circle Sector From Area to Arc Length (Closest Integer)

Topic 25

Part Circle - Full Area and Fraction to Part Area (Decimal)

Topic 26

Part Circle - Full Area and Fraction to Part Area (Pi Value)

Topic 27

Part Circle - Part Area and Fraction to Full Area (Decimal)

Topic 28

Part Circle - Part Area and Fraction to Full Area (Pi Value)

Topic 29

Circle Sector From Fraction to Area (Equation)

Topic 30

Circle Sector From Fraction to Area (Closest Integer)

Topic 31

Circle Sector From Fraction to Area (Closest Integer)

Topic 32

Circle Sector From Angle to Area (Equation)

Topic 33

Circle Sector From Angle to Area (Closest Integer)

Topic 34

Circle Sector From Angle to Area (Closest Integer)

Topic 35

Circle Donut From Both Radii to Area (Closest Integer)

Topic 36

Circle Donut From Inner Radius and Area to Outer Radius (Closest Integer)

Topic 37

Circle Donut From Outer Radius and Area to Inner Radius (Closest Integer)

Topic 38

Circle Sector From Arc Length to Area (Equation)

Topic 39

Circle Sector From Arc Length to Area (Closest Integer)

Topic 40

Circle Sector From Arc Length to Area (Closest Integer)

Topic 41

Circle Sector From Area to Fraction (Equation)

Topic 42

Circle Sector From Area to Fraction (Closest Integer)

Topic 43

Circle Sector From Area to Fraction (Closest Integer)

Topic 44

Circle Sector From Area to Angle (Equation)

Topic 45

Circle Sector From Area to Angle (Closest Integer)

Topic 46

Circle Sector From Area to Angle (Closest Integer)

Topic 47

Circle Sector From Area to Arc Length (Equation)

Topic 48

Circle Sector From Area to Arc Length (Closest Integer)

Topic 49

Circle Sector From Area to Arc Length (Closest Integer)

Topic 50

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

Topic 38

This math topic focuses on finding the inner radius of a donut shape given the outer radius and the total area of the donut. The topic is introduced as part of a beginner's unit on the geometry of circle areas, sectors, and donuts. Each question requires the student to calculate the inner radius using two provided pieces of information: the total area of the donut and the length of the outer radius. The answers are presented in a multiple-choice format, challenging the student to solve the problem and select the closest integer solution. This task strengthens skills in both geometry and algebraic manipulation.

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

View Unit

Circle Donut From Outer Radius and Area to Inner Radius (Closest Integer)

Complete these online problems with 80% or 4 correct answers in a row. Results are immediate.

Find the inner radius of the donut with an area of 150.8 and an outer radius of 8

r=8r=?