Flashcard 7- Area and Circumference of a Circle

Front

What is the formula for the circumference of a circle?

Back

The circumference (C) of a circle is given by the formula C = 2πr, where r is the radius.

Front

What is the formula for the area of a circle?

Back

The area (A) of a circle is given by the formula A = πr², where r is the radius.

Front

If the diameter of a circle is 10 inches, what is the radius?

Back

The radius is 5 inches, since the radius is half of the diameter.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

How do you convert diameter to radius?

Back

To convert diameter to radius, divide the diameter by 2.

Front

What is the circumference of a circle with a radius of 7 inches?

Back

The circumference is 43.96 inches, calculated using C = 2π(7).

Front

What is the area of a circle with a radius of 7 inches?

Back

The area is 153.94 square inches, calculated using A = π(7)².

Front

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

Back

The radius is 5 inches, calculated using r = C/(2π).

Front

What is the relationship between diameter and circumference?

Back

The circumference is π times the diameter (C = πd).

Front

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

Back

First, find the radius by dividing the diameter by 2, then use A = πr².