Question

what is the equation for circumference?
circumference = pi x radius (c = \pi r)
circumference = 2 x pi x diameter (c = 2\pi d)
circumference = pi x diameter (c = \pi d)
circumference = pi x radius, squared (c = \pi r^2)

6 fill in the blank 1 point
the formula to find the type your answer... of a circle is pi x radius squared.

7 multiple choice 1 point
diameter is ___ the radius.
1/2
2 times
1/3
3 times

8 multiple choice 1 point
if the radius of a circle is 18, the diameter must be
18
9
8
36

Explanation:

Identify the circumference formula

$$ C = \pi d \quad \text{or} \quad C = 2\pi r $$

Identify the area formula

$$ A = \pi r^2 $$

Relate diameter and radius

$$ d = 2r $$

Calculate diameter for radius 18

$$ d = 2 \times 18 = 36 $$

Answer:

Question 5

• Circumference = pi x radius (C = \(\pi\)r)
• Circumference = 2 x pi x diameter (C = 2\(\pi\)d)
• Circumference = pi x diameter (C = \(\pi\)d) (Correct answer)
• Circumference = pi x radius, squared (C = \(\pi\)\(r^2\))

Question 6

The formula to find the <blank>area</blank> of a circle is pi x radius squared.

Question 7

• 1/2
• 2 times (Correct answer)
• 1/3
• 3 times

Question 8

• 18
• 9
• 8
• 36 (Correct answer)