Triangle Maker: Make Triangles (Random or draw your own) and Measure the Area and Perimeter | | Instructions: | Suggested Lessons or Activities: | Special Features: | Other Related Modules and Useful Links:

Triangle Maker: Make Triangles (Random or draw your own) and Measure the Area and Perimeter

© R. Mirshahi


  • Click the triangle maker button with the arrow pointing to it to make a new right-angle triangle at random. You will see the triangle's measurements close to its sides and at the top of the page you will find the area and the perimeter. You can hide the area and perimeter by clicking the "eye" and click the ruler button to measure the sides to calculate the area and perimeter. Click the "eye" again to reveal the area and perimeter and check your answers (test yourself). You can also estimate before you measure and see how close you are. You can draw your own triangles (click and drag). Click eraser to make or draw different triangles. The measurements are rounded to the nearest cm.

Suggested Lessons or Activities:

  • This is a good resource for estimating and measuring area and perimeter.
  • Explore how you can calculate the area of a triangle (A = (bx h) ÷2) or multiply the height of the triangle by its base and divide the answer by 2
    and add all three sides to find the perimeter: P = side 1 + side 2 + side 3
  • Explore the concept of rounding to the nearest cm.
  • challenge students by asking them to draw a specific triangle.
  • ask the students to make a triangle at random and draw the same triangle in such a way that together you will have a rectangle.
  • In construction, sometimes they use a method called "3-4-5 triangle method" to create a right angle corner to make sure the shape of whatever you are building is a square or rectangle. Test this for yourself here!

As you click the reset button, the Main Activities Resource is loaded here. If you are looking for details and specific instructions and lesson ideas about the other activities, you need to go to the pages where these resources are housed.
  1. Angle Maker
  2. Line Maker
  3. Rectangle Maker
  4. Draw and Measure Lines and Angles
  5. Linear Measurement Test 20 Questions

Special Features:

  • random triangle maker (blue triangles)
  • ability to draw your own triangles (green triangles)
  • automatic measurements of sides, areas and perimeters
  • ability to hide area and perimeter
  • ability to annotate as well as draw triangles manually
  • interactive ruler (click the ruler button on the tool bar to show or hide ruler)
  • works really well with interactive whiteboards and Flash enabled tablets
  • full screen (minimize distractions as well as maximize the use of screen space)

Other Related Modules and Useful Links: