Khan Academy Wiki
Surface area
Surface-areas 256
Description
Exercise Name: Surface area
Math Missions: 6th grade (U.S.) Math Mission, High school geometry Math Mission
Types of Problems: 1

The Surface area exercise appears under the 6th grade (U.S.) Math Mission and High school geometry Math Mission. This exercise practices the calculation of surface area and lateral area for three dimensional geometric solids.

Types of Problems[]

There is one type of problem in this exercise:

  1. Find the surface area of the solid: This problem has a three dimensional object that is often from real-life. The user is asked to find the surface are of the object by and insert the answer in the space provided.
    Sa1

    Find the surface area of the solid

Strategies[]

This exercise can be completed with appropriate formulae, or by decomposing the shape into a net and finding the area of each side separately.

  1. The formula for the lateral area of a prism is the perimeter of the base multiplied by the prism height. Then the surface area is to add on the two base areas for top and bottom.
  2. The lateral area of a prism is half the perimeter of the base multiplied by the slant height. Pyramids have only one base for the surface area.
  3. On the triangular faces, information is given about the slant height so there is no need for additional calculation to find a different height. The relevant numbers are provided in the problem.
  4. Be careful, sometimes the problem asks for a surface area without a bottom, and sometimes it wants it with the bottom.

Real-life Applications[]

  1. Area and perimeter is used in many jobs for architecture and interior design.
  2. The ancient Egyptians from over 4000 years ago were very good at shapes and geometry. Every time the Nile burst its banks and flooded the planes, they had to use geometry to measure their gardens and fields all over again.