Lesson 1: Angles - Bisecting Angles with Compass and Ruler

   Constructing Knowledge

To bisect an angle is to split that angle into two equal parts. A second method for bisecting angles uses a compass and a ruler, using the following steps.

Step 1: Place the compass point on the vertex of the angle.

Step 2: Using the compass, draw an arc that cuts through both arms of the angle.

Step 3: Without moving the legs of the compass, put the compass point where the arc and the bottom angle arm intersect. Make an arc in the centre of the angle, through the original arc.

Step 4: Without moving the legs of the compass, put the compass point where the top arm and the original arc intersect. Make an arc in the centre of the angle, through both arcs.

Step 5: Connect the vertex of the angle with the point where the two small arcs intersect.

   Multimedia

A video describing FILL IN is provided.


EXAMPLE

Bisect the angle shown.



Solution


Step 1: Place the compass point on the vertex of the angle.



Step 2: Using the compass, draw an arc that cuts through both arms of the angle.



Step 3: Without moving the legs of the compass, put the compass point where the arc and the bottom angle arm intersect. Make an arc in the centre of the angle, through the original arc.



Step 4: Without moving the legs of the compass, put the compass point where the top arm and the original arc intersect. Make an arc in the centre of the angle, through both arcs.



Step 5: Connect the vertex of the angle with the point where the two small arcs intersect.



The angle is now bisected.


Now, it is your turn! Complete the questions in your Chapter 6, Lesson 1 Practice Makes Perfect that refer to Bisecting Angles with a Compass and Ruler.



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