Pre-Test		Post-Test
Q&A	Area and Perimeter	Q&A

Instruction Formulas |  Perimeter Formulas | Area Formulas | Three Dimensional Shapes and Surface Area | Volume Formulas | More Volumes and Areas | Formulas Involving Angles | Pythagorean Theorem

Instruction Formulas
CA GR6 AF 3.1 & 3.2, CA GR6 MG 1.1 CA GR7 MG 2.1

Now we will see how some basic formulas are applied. In reviewing the basic formulas, we will look at similar ones together. That is, we will present area formulas together, volume formulas together, etc. This is because you will see similarities in the various types of formulas which will help you recognize and remember them.

Perimeter Formulas
CA GR4 MS 1.4, CA GR5 MG 1.4, CA GR7 MG 2.1

The perimeter is the distance around the outside of a figure.  The result will come out in linear units, such as feet, yards, miles, etc.

Most often you will not need a formula to help find the perimeter of a non-curved structure. The perimeter is merely the total of the dimensions of the sides of a figure.

For rectangles you can express the perimeter as:

P = 2b + 2h

where b = the length of the base, h = the height.

Thus, If h = 4 ft. and b = 7 ft.

P = 2b + 2h would become

P = (2)(7ft.) + (2)(4 ft.)

P = 14 ft.+ 8 ft

P = 22 ft

The perimeter of a square can be expressed as:

P = 4s

where s = the length of a side.

Thus, If s = 5 ft.,

P = 4s would become

P = (4)(5 ft.)

P = 20 ft.

Finding the solution in a formula problem involves substituting number values into the formula and carrying out the Indicated math operations.

Another perimeter formula which is frequently used is the one for finding the perimeter of a circle. The perimeter of a circle is the same as the circumference of a circle. The formula to find the circumference of a circle is:

C = d (or) C = (2r)

where d = diameter of the circle
  r = radius of the circle
  = Pi which is (approximately) 3.1416

(You will see Pi represented as or , as 3.14, or 3.1416, as 3.14159, and other values carried out even further. Actually, the constant Pi is the number of times that the diameter of any circle will go into the circumference of that circle. It does not come out even.  Many calculations where great accuracy is required use the value 3.14159 for Pi.)

If the diameter of a circle were 8 ft., then:

C = d would become

C = (3.1416) (8 ft.)

C = 25.1328 ft.,  and this is the perimeter of a circle with a diameter of 8 ft.

Now, let's stop and take Practice Exercise 9-1 (top)

Note: Step by step solutions to these Practice Exercises are provided at the end of the instruction section.

www2.funbrain.com/cgi-bin/poly.cgi?A1=s&A2=2&A15=1&INSTRUCTS=1.

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