Circumference and Area of Circles (Basic)

Front

What is the formula for the area of a circle?

Back

Area = π × r², where r is the radius.

Tags

CCSS.7.G.B.4

Front

What is the value of π (pi) commonly used in calculations?

Back

3.14

Tags

CCSS.HSG.GMD.A.1

Front

How do you find the radius of a circle if you know the diameter?

Back

Radius = Diameter ÷ 2.

Tags

CCSS.7.G.B.4

Front

What is the formula for the circumference of a circle?

Back

Circumference = 2 × π × r or Circumference = π × d, where d is the diameter.

Tags

CCSS.7.G.B.4

Front

If the radius of a circle is 7 inches, what is the area?

Back

Area = π × (7)² = 3.14 × 49 = 153.86 in².

Tags

CCSS.7.G.B.4

Front

If the circumference of a circle is 31.4 inches, what is the radius?

Back

Radius = Circumference ÷ (2 × π) = 31.4 ÷ (2 × 3.14) = 5 inches.

Tags

CCSS.7.G.B.4

Front

What does the term 'diameter' refer to in a circle?

Back

The diameter is the distance across the circle through the center, equal to twice the radius.

Tags

CCSS.HSG.C.A.2

Front

If the area of a circle is 78.5 square units, what is the radius?

Back

Radius = √(Area ÷ π) = √(78.5 ÷ 3.14) = 5 units.

Tags

CCSS.7.G.B.4

Front

What is the relationship between the radius and diameter of a circle?

Back

The diameter is always twice the length of the radius.

Tags

CCSS.7.G.B.4

Front

How do you convert the radius to diameter?

Back

Diameter = 2 × Radius.

Tags

CCSS.7.G.B.4