Circle area - Math Central

HOME

Math Central

Quandaries & Queries

Question from marlena, a student:

Ok, i do not see how to get the area of circles! they give you the circumfrance
which is 43.96cm and then u have to find the radius and area. I got the area right
which was 7cm but then i got 21.98 for a area and the real answer was 150.39cm
What did i do wrong?-A confused math student

Marlena,

The area of a circle is π times the square of the radius, that is π r². You found r to be 7 cm and then calculated π times r rather than π times r².

Penny

Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.