General Math On-line

 Chapter 5 Calculator Skills, Formulas, Geometry

 What will I be able to do when I finish this chapter?

Use order of operations.

Evaluate formulas.

Solve direct and inverse proportion problems.

Measure angles.

Determine length, circumference, and perimeter of two-dimensional shapes.

Determine area of two-dimensional shapes.

Determine volume of three-dimensional shapes.

Solve application problems.

 

Chapter 5 Tips and Hints:

In this chapter you will be using formulas. A formula is a mathematical machine that does a particular job over and over. The formula for finding the area of a rectangle is as follows: Area = Length x Width. You can use this formula to find the area of any rectangle regardless of size by multiplying the length times the width. Just like a machine, a formula will do the same job again and again provided you give it the correct starting materials and know how to operate it.

 

Show your all your work when evaluating a formula.For example, if you wanted to calculate the area of a rectangular tabletop that is 5 feet long and 3 feet wide you would follow the steps below.

1. Write down the appropriate formula.

Area = Length x Width

2. Replace the variables (unknowns) with the appropriate numbers.

Area = 5 feet x 3 feet

3. Perform the calculation.

Area = 15 square feet

Pay attention to the units of measure on your answer. In the problem above, the number 15 by itself doesn't tell us anything. It could be 15 square inches, 15 square yards, or 15 square miles. The answer would be meaningless without the units square feet. Don't forget the units.

 

There is no need to spend time memorizing formulas. On the test you will be given the formula you need or you will be able to look it up in your textbook. Concentrate on learning how to use a formula that is given to you.

 

In this chapter you will solve problems using proportions. Proportions work by comparing pairs of things. Example 1: You could set up a proportion comparing the number items purchased to the total price. Example 2: You could set up a proportion comparing the number of people working on a project to the time it takes to complete the project. To be successful using proportions you must be able to do two things.

1. Distinguish between a direct proportion and an inverse proportion. If one member of the pair goes up and the other goes up as well this is a direct proportion. If one member of the pair goes up and the other goes down this is an indirect proportion. Example 1 above is a direct proportion. The more you buy the more it costs. Example 2 is an inverse proportion. The more people you have working the less time it takes to do the job.

2. Direct and Inverse Proportions are set up differently. Make sure know to set up both types of proportions.

There is a great deal of time in this chapter devoted to calculator usage. Keep in mind that every model of calculator is slightly different. The directions in your textbook may describe some of your calculator's functions perfectly. Sometimes you may need to go to the manual that came with the calculator for more information. A "Direct Algebra Logic (DAL)" calculator functions quite differently from the directions in the textbook.

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