Help on circumference and area of circles?

Question

r=2.6m what is the circumference?

d=80 ft. what is the area?

d=1.4 cm. What is the area?

r=18 in. What is the circumference?

r=7.5 mm. What is the circumference?

Answer 1

These are easy. Just look up the formulas and plug the numbers in circmference is 2*pi*r. so r=2.6m would be 2X2.6X3.14. The areas have to be in your math book or just google circle area formula. I think it is pi*r^2.

Answer 2

To find the circumference of a circle you must multiply two times pi (3.14) time the radius.
If re = 2.6m that means r is the radius so
C= (2)(2.6)(3.14) parentheses mean multiply
C= 16.328

The diameter is twice the radius
if d=80 then r = 40
C=(2)(40)(3.14)
C251.2

d=1.4 then r=.7
C=(2)(.7)(3.14)
C=4.396

C=(2)(18)(3.14)
C= 113.04

C=(2)(7.5)(3.14)
C=47.1

Answer 3

Do you have a calculator? Circumference = π*d, d = 2*r, area = π*r^2.

Answer 4

Circumference formula: 2*pi*r
Area Formula: pi*r^2
The radius is exactly one-half the length of the diameter.

so: (all answers are rounded to the nearest thousandth)
a) 16.336 m
b) 5026.548 ft^2
c) 1.539 cm^2
d) 113.097 in
e) 47.124 mm

Answer 5

circumference equals 2 times the radius time pie or pie times diameter.

Area is equal to pie times radius squared
or pie times one half diameter squared.

Answer 6

circumference = 2 times radius times pi so 2 x 2.6 x pi, use 3.14 for pi if your book tells you to

area = radius times itself times pi, so divide diameter by 2 to get radius (0.7) then times it by itself then times pi

Answer 7

Circumference is 2 * PI * radius of the circle

Area is PI*r*r where r is radius of circle.

C = 2*PI*r
A = PI*r*r

Answer 8

1)C=21.2264m
2)125.6ft.
3)D=2.198cm.
4)1017.36in.
5)176.625mm.