There are a couple of techniques you might be expected to know for drawing a proper good triangle.

Drawing A Triangle If You Have 3 Sides

Example: Draw the triangle DEF with sides 7cm, 6cm and 5cm.

  • Use a ruler to draw a 5cm line and label one end D and the other E
  • Open your compass to 6 cm
  • Place the compass on point D and draw an arc above the line
  • Open your compass to 5 cm
  • Place the compass on point E and draw an arc above the line. Where the arcs cross is point F
  • Join up the points of the triangle

Drawing A Triangle When You Have A Sides And Two Angles

Example: Draw the triangle GHI with one side 6cm and angles of 55° and 70°.

  • Draw a line of 6cm with a rule. Label one end G and one end H
  • Place centre of protractor at point G. Make sure it is lined up. Measure an angle of 55° and mark it with a dot. Join point G to the dot with a ruler.
  • Place centre of protractor at point H. Measure an angle of 70° and mark with a dot. Join point H to the dot with a ruler.
  • If the lines don’t cross extent them until they do.