Help to understand the dimater,circumfrance of the circle?

Question

im 15 and i no nothing at all about it

please help me to explain

and how to work out the area and circumfrance of the circle

and alos to cicrles where they have bits missing

dont say "your 15 and cant spell - i can spell but i just wrote this really quickly

or your dumb -im not i just havent been taught this stuff

Answer 1

circumference is the distance around the circle

radius is the distance across the circle

diameter is one half the radius

A = 3.14  x  r squared

Answer 2

twinkle twinkle little star

the circumference of a circle is

2 pi r  

Answer 3

for circles

A = pi*r^2

Circumference = perimeter of circle = 2pi*r

where

pi = 3.1416

r = radius of circle