11.4: Polygons

1) Lesson Objectives:

You should be able to

• distinguish what are polygons

• find the sum of interior angles of any n-sided polygons

• find the sum of exterior angles of any n-sided polygons

• find the each interior angle of a regular n-sided polygons

• find the each exterior angle of a regular n-sided polygons

Terminologies

• regular polygons

• interior angles

• exterior angles

A: What are polygons?

B: Regular polygons

Read and try to understand Textbook 1B explanations and worked examples: pg 122 to 124.

C: Sum of interior angles of polygon

Read and try to understand Textbook 1B explanations and worked examples: pg 124 to 126.

D: Sum of exterior angles of polygon

Read and try to understand Textbook 1B explanations and worked examples: pg 126 to 131.

NOTE: Refer to TB pg 127. Scan the QR code under Investigation to self explore on Exterior angles of polygon using geometry software.

E: Line of symmetry

Read and try to understand Textbook 1B explanations and worked examples: pg 132 to 133.

F: Rotational symmetry

Read and try to understand Textbook 1B explanations and worked examples: pg 133 to 134.

NOTE:

Order of rotation: Refers to the number of times a figure rotates and fit onto the original shape. All figures will have at least One order of rotational symmetry as it goes 360 deg.