Drawing Angles Slideshow 41, Mathematics Mr Richard Sasaki Room 307

OBJECTIVES Understand how to draw 90 o and 60 o angles Understand how to bisect and add to these to make other angles (such as 30 o and 120 o )

DRAWING ANGLES I’m starting to see people with set squares helping them draw angles. Remember, you must use a compass!

90 O ANGLE So far, we have constructed some shapes and bisected lines and angles. Today we will draw some angles. We already know how to draw a 90 o angle so today we will use a slightly different method. (There are quite a few different ways to do this.)

90 O ANGLE Draw and label a right-angle with line segments of any length starting at vertex A. Label a point D somewhere above and close to the line segment. Make distance AD the radius of the compass.

90 O ANGLE Next, draw an arc from D that passes through the line segment, point A and above point A again. Draw a line segment from the new crossing made, through D and then up to the point above A. Draw a line segment from A to the point above it… And finally, remove the line passing through D! Don’t forget to label it! Try Q1 – 4!

60 O ANGLE From the point made, draw a mark over the arc and then join this mark to point P. R 60 o

30 O ANGLE You can just simply cut the 30 o angle in half, but there is a quicker way! Place the point at S and cross the arc. Make a point T.

30 O ANGLE Place the point at T and cross over the new point. Label this point R. 30 o Try Q5 – 9!