Understanding Circles: Circumference and Area

What is the formula for the circumference of a circle using its diameter?

• πr²

• 2πr

• d/2

• πd

What is the relationship between the circumference and the diameter of a circle?

• Circumference is the same as the diameter

• Circumference is half the diameter

• Circumference is twice the diameter

• Circumference is π times the diameter

How can the area of a circle be visualized using a parallelogram?

• By cutting the circle into squares

• By dividing the circle into sectors and rearranging them

• By drawing a rectangle around the circle

• By folding the circle in half

What is the formula for the area of a circle?

• πd

• πr²

• 2πr

• r²

If the circumference of a circle is 26π, what is the radius?

• 26

• 6.5

• 13

• 52

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

• Multiply the radius by 2

• Divide the radius by 2

• Multiply the radius by π

• Square the radius

Given an area of 18π for a circle, what is the radius in simplest radical form?

• 3√2

• 18

• 6√2

• 9

How far does a rider travel on a Ferris wheel with a 42-foot diameter in 4 minutes if it rotates every 20 seconds?

• 840 feet

• 1583.36 feet

• 126π feet

• 42π feet

What is the angle of each sector in a regular octagon inscribed in a circle?

• 60 degrees

• 45 degrees

• 90 degrees

• 30 degrees

In a 45-45-90 triangle, if the hypotenuse is R, what is the length of each leg?

• R/√2

• R

• R√2

• R/2