Find the circumference and area of a circle with a diameter of 7cm. Round your answers to the hundredth.?

Question

C = 21.98cm and A = 38.47cm squared

C = 21.98cm and A = 153.86cm squared

C = 43.96cm and A = 38.47cm squared

C = 43.96cm and A = 153.86cm squared

Answer 1

circumferenceof circle is C= 2pi r and area is A= pir^2
r is radius, r = diameter/2

r= 7/2 = 3.5 cm

C= 2pi*3.5 = 21.98 cm

A= pi(3.5)^2 = 38.47 cm^2

the correct answer is the first one

Answer 2

Circumference of circle = 2*Pi*R or Pi*D (where R is the radius and D is the diameter,) Pi = 3.14159

Area of circle = Pi*R^2 or Pi* D^2/4

Circumference of circle = 3.14159 * 7 = 21.99 cm

Area of circle = 3.14159 * 7 * 7 / 4 = 38.48 square cm

First answer is closest considering rounding

Answer 3

C = π x 7 = 22 / 7 x 7 = 22 cm
A = π x 3.5 ² cm ²
A = 38.47 cm ²

Answer 4

OK the formula for finding the Circumference is:
C=d(pi)

The formula for are is:
A=r^2(pi)

---So to find the C:

C=7(pi)
C=21.98cm

---To find A:

A=3.5^2(pi)
A=12.25(pi)
A=38.47cm^2


So the first answer form the top is correct.