Area of Circles and Parts of Circles Flashcardizz

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

How do you find the area of a semicircle?

Back

To find the area of a semicircle, use the formula A = (1/2)πr², where r is the radius.

Front

What is the area of a quarter circle?

Back

The area of a quarter circle is calculated using the formula A = (1/4)πr², where r is the radius.

Front

If the diameter of a semicircle is 8 cm, what is its radius?

Back

The radius is half of the diameter, so the radius is 4 cm.

Front

Calculate the area of a semicircle with a radius of 4 cm.

Back

A = (1/2)π(4)² = 25.12 cm².

Front

What is the area of a quarter circle with a radius of 6 cm?

Back

A = (1/4)π(6)² = 28.26 cm².

Front

How do you round a number to the nearest hundredth?

Back

To round to the nearest hundredth, look at the third decimal place. If it's 5 or more, round up the second decimal place by one.

Front

What is the area of a quarter circle with a radius of 18 cm?

Back

A = (1/4)π(18)² = 254.34 cm².

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 value of π (pi) to two decimal places?

Back

π (pi) is approximately 3.14.