area and circumference of circles

Front

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

Back

r = d/2, where r is the radius and d is the diameter.

Front

What is the definition of diameter in a circle?

Back

The diameter is the distance across the circle through the center.

Front

What is the formula for calculating the area of a circle?

Back

A = πr², where A is the area and r is the radius.

Front

How do you calculate the circumference of a circle?

Back

C = 2πr or C = πd, where C is the circumference, r is the radius, and d is the diameter.

Front

If the radius of a circle is 15 cm, what is the area?

Back

706.5 cm² (rounded to the nearest tenth).

Front

If the diameter of a circle is 20 cm, what is the radius?

Back

r = 10 cm (since r = d/2).

Front

What is the circumference of a circle with a radius of 14 inches?

Back

Approximately 87.96 inches (using C = 2πr).

Front

What is the value of π (pi) to two decimal places?

Back

3.14.

Front

How does increasing the radius of a circle affect its area?

Back

The area increases quadratically as the radius increases.

Front

What is the relationship between diameter and circumference?

Back

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