Page 71 - NUMINO Challenge_B2
P. 71
8 Tessellation
Basic Concepts Sum of the Interior Angles of a Polygon
Draw a line that is parallel to the base of a triangle and passes through the
vertex. Since alternate angles of parallel lines are equal, the sum of the
interior angles of a triangle is 180 .
Use the sum of the interior angles of a triangle to find the sum of the interior
angles of various polygons.
Polygon
Number of Triangles Triangle Rectangle Pentagon Hexagon
1 2 3 4
Sum of the Interior
Angles 180 360 540 720
Therefore, the sum of the interior angles of a sided polygon is ( 2) 180 .
Example What is the measure of each angle of an equilateral octagon?
Class Notes triangles.
Octagons can be split into
The sum of the interior angles of a triangle is . The sum of the interior angles of
triangles is
The sum of the interior angles of an octagon is . An equilateral octagon has
eight equal angles. Therefore, the measure of one angle is .
68 NUMINO Challenge B2
Basic Concepts Sum of the Interior Angles of a Polygon
Draw a line that is parallel to the base of a triangle and passes through the
vertex. Since alternate angles of parallel lines are equal, the sum of the
interior angles of a triangle is 180 .
Use the sum of the interior angles of a triangle to find the sum of the interior
angles of various polygons.
Polygon
Number of Triangles Triangle Rectangle Pentagon Hexagon
1 2 3 4
Sum of the Interior
Angles 180 360 540 720
Therefore, the sum of the interior angles of a sided polygon is ( 2) 180 .
Example What is the measure of each angle of an equilateral octagon?
Class Notes triangles.
Octagons can be split into
The sum of the interior angles of a triangle is . The sum of the interior angles of
triangles is
The sum of the interior angles of an octagon is . An equilateral octagon has
eight equal angles. Therefore, the measure of one angle is .
68 NUMINO Challenge B2
