In geometry, there is area. And there is also surface area. Surface area is used to find the sum of all the areas of all the shapes of an object. These objects are usually three-dimensional.
It is very easy to calculate surface area. The hardest part is probably selecting the correct formula to use. There are two types of surface area: lateral and total. And there is a formula for each type for each type of shape. Lateral surface area is the sum of all the shapes except the bases. The total surface area is the sum of all the shapes including the bases.
Lateral: faces Total: faces and bases
When lateral surface area is requested, it is usually stated. Sometimes, it does not state which type of surface area to calculate. In this case, you calculate the total surface area. The formula for total surface area includes the formula for lateral surface area also. So when you are required to calculate both lateral and total, calculate the first half of the formula; this will be your lateral surface area. Then calculate the second half only for total surface area; this amount will be added to the lateral to find the total amount.
Steps to take to calculate surface area:
- Determine the shape of the object.
- Select the correct formula(s) for surface area.
- Substitute for the variables.
- Remember that ‘h’ is the height of the object, not the height of the base. ‘P’ is the perimeter of the base. ‘B’ is the area of the base.
- Once you substitute, complete the calculations.
Remember to write your answer in square units.
Check out these examples.
**If diameter is given, divide it by 2 to get the radius.
**For Perimeter, add the sides. You must double the length and width if the base is a rectangle. Multiply the side length by 4 if it is a cube.
Tune in next week for Part 2 of this math tip!