Aim: How do we find the area of a circle?

(3-20-2012)Aim: How do we find the area of a circle?

Circle Area Conjecture
   The area of a circle is given by the formula A= πr^2, where A is the area and r  is the radius of the circle.
  The circumference of the circle is given by the formula C=πd.  Where c is the circumference and d is the diameter of the circle.

Area Example

A= πr^2
      π4^2(4*4)
      Answer:16πcm^2
          or
   Answer:16π= 50.24cm^2












Circumference example

A chocolate chip cookie has a diameter of 3in and a butterscotch cookie has a diameter of 5in. How much larger in circumference of the butterscotch cookie is to the chocolate chip cookie?

                         C= πdChocolate chip: C=3π in
 Butterscotch:    C=5π in
                         5π -3π= 2π in^2
                         Answer: 2π in^2 
                             or
Chocolatechip: 3π = 9.42 in
Butterscotch:   5 π = 15.7 in
                       15.7-9.42= 6.28
                        Answer: 6.28 in^2
              Answers: 2π in^2 or 6.28 in^2

TRY IT YOURSELF:
          A circle has the diameter of 14cm. What is the circumference and area of the circle?
*Remember the radius is half the diameter.   

Answer: 

Circumference: 14π 

Area: 196π