This document provides instructions for students to practice geometric constructions using a straightedge and compass. It includes how to construct angles of 60, 120 degrees and bisectors of angles. Students will learn to construct angles with specific measurements and draw angle bisectors. The lesson explains the steps and includes examples of constructing different angles and their bisectors on example line segments.

1. Subject : Mathematics Topic : Geometrical Construction Form : Two Duration : 45 minutes Learning Objective: Constructions Using a Straight Edge and a Pair of Compasses

2. Learning Outcomes : At the end of lesson, students should be able to Construct the angle of 60  and 120  Construct bisector of an angle.

3. Prerequisite knowledge : Students have already know Construct a line segment of given length. Construct a triangle given the length of the sides. Construct a perpendicular to a line. The perpendicular bisector of a given line segment. The perpendicular to a line through a point on the line. The perpendicular to a line passing through a point not on the line. Approach : Constructive Learning

4. Draw the angle of 60  using the protractor A Then, label point C at the 60  mark using the outer scale. Remove the protractor. Join BC. B C 60  Draw a line AB. 2. Place the base line of the protractor on AB. 3. Place the centre of the protractor on the point B. 5. An angle of 60  is drawn.  ABC = 60 

5. Construct an angle of 60° Construct  ABC = 60° B C A 60° (a) Draw a straight line and mark the point B . (b) With B as the centre, use a compass to draw a big arc to cut the line at C . (c) With the same radius and with C as the centre, cut the first arc at A . (d) Join A to B .  ABC = 60°

6.  LMN = 60°  PQR = 60° P 60° L 60° Draw a line AB of 5 cm. Construct an angle of 60° at A. A B 60° 5 cm

7. Construct an angle of 120° Construct  BAD = 120° A B C 120° D  BAD = 120° Draw a straight line and mark the point A . (b) With A as the centre, use a compass to draw a big arc to cut the line at B . (c) With the same radius and with B as the centre, cut the first arc at C . (d) With the same radius and with C as the centre, cut the second arc at D . (e) Join A to D .

8. Construct an angle of 120° Construct  ABD = 120° B C A 60° D 120° Draw a straight line and mark the point B . (b) With B as the centre, use a compass to draw a big arc to cut the line at C . With the same radius and with C as the centre, cut the first arc at A . Join A to B . Mark the point D at the other side of the line.  ABD = 120°

9. Draw a line PQ of 6 cm. Construct an angle of 120° at Q. P Q 60° 6 cm  XYZ = 120°  MLN = 120° Z 120° Z 120° 120°

10. Construct the bisector of an angle Construct the bisector of  ABC . P Q R With B as the centre, use a compass to draw arcs to cut AB and BC at P and Q . (b) Without changing the radius and with P and then Q as the centre, draw arcs to cut at R . (c) Join R to B . BR is the bisector of  ABC . B A C

12. Construct an angle of 30° Construct an angle of 60° 30° then construct the angle bisector.

13. Construct an angle of 45° Construct an angle of 90° 45° then construct the angle bisector.

14. 15° 15° 22 ° 22.5°

15. 150° 30° 150°

16. 75° C 120° D