The document is about polygons and includes the following key points: 1. A polygon is a plane figure bounded by straight lines. There are two types of polygons: irregular polygons where the sides and interior angles are unequal, and regular polygons where the sides and interior angles are equal. 2. The name of different polygons is given based on the number of sides, such as triangle for 3 sides, quadrilateral for 4 sides, and pentagon for 5 sides. 3. The sum of the interior angles of a polygon is (n-2) x 180 degrees, where n is the number of sides. The sum of the exterior angles is always 360 degrees.

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POLYGON
By
Airil Bin Ahmad
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Polygon is a plane figure bounded by
straight lines
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2. There are 2 types of polygon:
a. Irregular Polygon
A polygon in which not all the sides
are of equal length or not all the
interior angles are of equal sides.
1200
300 300
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b. Regular Polygon
A polygon in which all the sides
are of equal length and all the
interior angles are of equal size.
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Interior Angle
a b
Angles a, b, c and d
d c are interior angles.
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3.The name of polygon :
No.of side Name of figure No.of triangle Sum of interior angles
(n) n -2 (n -2) x 180
3 Triangle 3–2= 1 (3 -2) x 180 = 1800
4 Quadilateral 4–2= 2 (4 -2) x 180 = 3600
5 Pentagon 5–2= 3 (5 -2) x 180 = 5400
6 Hexagon 4 7200
7 Heptagon 5 9000
8 Octagon 6 10800
9 Nonagon 7 12600
10 Decagon 8 14400
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a0 + b0 + c0 = 1800
c0
a0 b0
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a0 + b0 + c0 = 1800 0
x0 + y0 + z0 = 1800
c0
a0
z0
b0 y0
x0
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a0 + b0 + c0 = 1800 0
q0 + r0 + s0 = 1800
x0 + y0 + z0 = 1800
b r00 y0
a0 z0
c0 x0
q0 s0
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MATHEMATICS G
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Exercise:
1. Find the sum of the interior angle of each of the
following regular polygons:
a. 12-sides b. 26-sides
c. 22-sides d. 36-sides
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Exercise: 2. Find the value of x:
x0 + + + + = 540 1200
x + 455 = 540 x0 1000
0
x = 5400- 455
x = 850 1100
1250
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3. Find the value of x: 4. Find the value of x:
1250 1390
1180 1020 x0
1290 x0 1130 1310
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5. Find the value of x: 6. Find the value of x:
1020 1090
1250 1020
x0 2390
650 x0
1130 1010
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7. Find the value of x: 8. Find the value of x:
x0 1030 2x0
1250 1020
2x0 2390
950 x0
1150 1030
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SUM OF EXTERIOR
ANGLES
By
Airil Bin Ahmad
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e
f
Angles e, f, g and h
h are exterior angles.
g
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c
b
d Exterior
Angle
a
e
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c a+b+c+d+e=3600
b
d
a
e
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SUM OF EXTERIOR
ANGLES = 360 0
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Solving Problem Example 1: Find the value of x:
+ + + + = 360 600
x + 28500= 3600
- 285 800
x = 360 0 x0
x = 750
700
750
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Solving Problem Example 2: Find the value of x:
+ + + + = 360 650
x + 27100= 3600
- 271 800
x = 360 0 x0
x = 890
560
700
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Example 3: Find the value of x:
65 0
+ + + + = 360 0 1150
800
x + 271 00 = 360 0
- 271
x0
x = 360 0
1100 1240 560
X = 89 0
700
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EXERCISE
 PG 28
 EX 2.2C
 NO 1, 2 AND 3
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NO. OF SIDES
By
Airil Bin Ahmad
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No.of sides(n)=
360 ÷ exterior angle
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Example 1: Find the no. of sides if :
1 a. Exterior angle = 600
n = 3600 ÷ 600
= 6 = Hexagon
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Example 2: Find the no. of sides if :
1b. Interior angle = 1400
Exterior angle = 1800 – 140=40
n = 3600 ÷ 400
= 9 = Nonagon
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Exercise:
Find the no. of sides in each of the regular polygons.
1. 2.
450 360
3. 4.
400 200
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Exercise:
Find the no. of sides in each of the regular polygons.
5. 6.
1600 1440
7. 8.
1700 1080
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SOLVING PROBLEM
OF POLYGONS
By
Airil Bin Ahmad
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EXERCISE:
1. 2. X0
X0
Y0 Y0
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EXERCISE:
3. 4.
Y0 Y0
X0
X0
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5. In the regular polygon, find x0 and y0 6. In the regular polygon, find x0 and y0
y0
x0
y0
x0
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