Circle Flashcard

Front

What is the formula for the circumference of a circle?

Back

Circumference = π × diameter (C = πd) or Circumference = 2 × π × radius (C = 2πr)

Front

What is the formula for the area of a circle?

Back

Area = π × radius² (A = πr²)

Front

How do you find the radius if you know the diameter?

Back

Radius = Diameter / 2

Front

What is the diameter of a circle?

Back

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

Front

What is π (pi)?

Back

π (pi) is a mathematical constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

If the radius of a circle is 7 cm, what is the circumference?

Back

Circumference = 2 × π × 7 cm ≈ 43.98 cm

Front

If the radius of a circle is 5 in, what is the area?

Back

Area = π × (5 in)² ≈ 78.54 in²

Front

What is the area of a semi-circle?

Back

Area of a semi-circle = (π × radius²) / 2

Front

If the diameter of a circle is 10 m, what is the area?

Back

Area = π × (5 m)² ≈ 78.54 m²

Front

What is the relationship between radius and diameter?

Back

The diameter is twice the radius (Diameter = 2 × Radius).