**Important Concepts and Formulas**

1. We use the tools of a geometry box to
construct shapes such as line segments, angles, circles etc.

2. Various instruments used in
constructions are ruler, a pair of compasses and protractor.

3. Using a protractor, we can construct angles
of the given measurement.

5. Angles 30°, 45°, 75°, 90°, 135°,
150°, etc., are constructed using the concept of angle bisectors.

6. Circles of given radius can be
constructed easily using a pair of compasses.

7. We can draw perpendicular to a line
segment from a point on the given line segment.

8. We can draw perpendicular to a line
segment from a point outside the given line segment.