Finding the Circumference

Front

What is the formula for finding the circumference of a circle?

Back

C = π·d, where C is the circumference and d is the diameter.

Front

What does the symbol π (pi) represent?

Back

Pi is a mathematical constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

What is the diameter of a circle?

Back

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

Front

How do you calculate the circumference if you know the radius?

Back

Use the formula C = 2πr, where r is the radius.

Front

If the radius of a circle is 10 cm, what is the circumference?

Back

C = 2π(10) = 20π cm or approximately 62.8 cm.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the length of the radius: d = 2r.

Front

If the circumference of a circle is 31.4 cm, what is the diameter?

Back

Using C = π·d, d = C/π = 31.4/3.14 = 10 cm.

Front

What is the circumference of a circle with a diameter of 12 cm?

Back

C = π·d = π·12 = 12π cm.

Front

What is the radius of a circle with a circumference of 31.4 cm?

Back

Using C = 2πr, r = C/(2π) = 31.4/(2π) = 5 cm.

Front

What is the circumference of a circle with a radius of 5 cm?

Back

C = 2π(5) = 10π cm.