Construction of Angles

Construction of a Right Angle:

Steps:

i. Draw line AB.

ii. Draw a line that extends Outwards from A

iii. Choosing a convenient radius, draw a semi-circle CD with centre A.

iv. With centres C and D and any radius of your choice, draw arcs to intersect at E

v. Draw a line from A to E. This line will be perpendicular to AB and form a 90° angle.

Construction of Angle 45°:

Steps:

i. First Construct a 90° angle following the steps above.

ii. Bisect the right angle to get a 45° angle.

Or

Draw line AD = 100mm, with a tee-square

Slide your tee-square below the line and place the 45°/45° set-square on the tee-square.

Using any of the 45° sides, draw a line AC

Construction of Angle 60°:

Steps:

i. Draw line AB

II. Indicate point C anywhere on AB

iii. Choose a convenient radius and draw an arc from centre C to cut AB at D

iv. With centre D and the same radius you chose in the previous step, draw an arc to cut the previous arc at E.

v. Draw a line from C through E, i.e line CF. Angle FCB is 60°

Construction of Angle 30°:

Steps:

i. Construct an angle of 60^o like we did above.

ii. Bisect the 60^o angle. Angle FBD is 30°

Construction of Angle 15°:

Steps:

i. Construct an angle of 30°.

ii. Bisect the 30° angle. Angle FCB is a 15° angle.

Construction of Angle 120°:

Steps:

i. Construct a 60° angle.

ii. With centre E, and the same radius used to construct the 60° angle, draw another arc to cut at G.

iii. Draw a line from C through G, i.e line CH. HCB is a 120° angle.