1. A Regular Polygon Carmelo Ellul Head of Department (Mathematics)
A powerpoint presentation by
Carmelo Ellul
Head of Department (Mathematics)

2. 360º ÷ 5 = 72º A Regular Polygon Task:
Inscribe a regular pentagon in a circle of radius 3 cm. 1 2 3 4 5 6 7 8 9 cm B
Draw any radius OA.
A pentagon has 5 sides.
Therefore divide 360º (the angle at centre)
by 5.
Draw a circle of radius 3 cm.
Repeat drawing angles of 72º on each new line (radius) drawn; OB, OC, OD and OE .
With your protractor draw an angle of 72º on the radius OA. C O A D
360º ÷ 5 = 72º E

3. 360º ÷ 5 = 72º A Regular Polygon Task:
RESTART
END SHOW
Task:
Inscribe a regular pentagon in a circle of radius 3 cm. A B C O D E
Join AB, BC, CD, DE and EA.
ABCDE is the required pentagon.
360º ÷ 5 = 72º