area and circumference

Front

What is the formula for the area of a circle?

Back

The area of a circle is calculated using the formula A = πr², where A is the area and r is the radius.

Front

What is the formula for the circumference of a circle?

Back

The circumference of a circle is calculated using the formula C = 2πr or C = πd, where C is the circumference, r is the radius, and d is the diameter.

Front

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

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

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

Back

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

Front

How do you convert the circumference of a circle to find the radius?

Back

To find the radius from the circumference, use the formula r = C/(2π), where C is the circumference.

Front

What is the approximate value of π (Pi)?

Back

The approximate value of π is 3.14.

Front

If the radius of a circle is doubled, how does the area change?

Back

If the radius is doubled, the area increases by a factor of four, since area is proportional to the square of the radius.

Front

What is the relationship between diameter and radius?

Back

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

Front

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

Back

To find the area using the diameter, first calculate the radius (r = d/2), then use the area formula A = πr².

Front

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

Back

The circumference is C = 2π(5) = 10π cm, approximately 31.4 cm.