Ratios and Pi

Front

What is a ratio?

Back

A ratio is a comparison of two quantities, showing how many times one value contains or is contained within the other.

Front

What is the value of pi (π)?

Back

Pi (π) is approximately 3.14 and represents the ratio of the circumference of a circle to its diameter.

Front

What is the formula for the circumference of a circle?

Back

Circumference = 2πr, where r is the radius of the circle.

Front

What is the formula for the area of a circle?

Back

Area = πr², where r is the radius of the circle.

Front

If the radius of a circle is 18 cm, what is the circumference?

Back

Circumference = 2π(18) ≈ 113.04 cm.

Front

If the circumference of a circle is 21 cm, what is the radius?

Back

Radius = Circumference / (2π) ≈ 3.34 cm.

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 a ratio into a fraction?

Back

To convert a ratio into a fraction, write the first quantity as the numerator and the second quantity as the denominator.

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

If Circle Q has a circumference of 21 cm and Circle P has a radius of 3 cm, what is the ratio of their circumferences?

Back

The ratio is 7:3.