Polygons Flashcards
What is a polygon?
A 2D many sided shape
(3 or more straight lines)
What is meant by a regular polygon?
All the sides are equal
All the angles are equal
What is an irregular polygon?
The sides and angles are not equal
How do you calculate an exterior angle of a regular polygon?
360 divided by the number of sides
What are the two methods of calculating an interior angle of a regular polygon?
Exterior angle = 360 / number of sides
Interior angle = 180 subtract the exterior
or
Sum of interior angles = The number of triangles the shape splits into (sides - 2) multiplied by 180
One interior = Sum of interior / number of sides
How do calculate the number of sides of a regular polygon from an exterior angle?
360 / size of exterior angle
How do you calculate an interior angle from an exterior angle?
180 subtract exterior angle
What steps are needed to calculate y?
Subtract 2 from the number of sides to find how many triangles it splits into.
Multiply this by 180 to find the sum of interior angles.
Subtract from this the sum of the other angles to find y.
What steps are needed to calculate y?
Exterior angle of pentagon = 360/5.
(72)
Interior angle of pentagon = 180 - exterior.
(108)
360 - sum of the three interior pentagon angles. (angles around a point add to 360)
(36)
Name the polygons from 3 sided to 10 sided
3 sided = Triangle
4 sided = Quadrilateral
5 sided = Pentagon
6 sided = Hexagon
7 sided = Heptagon
8 sided = Octagon
9 sided = Nonagon
10 sided = Decagon
What steps are needed to find x?
Exterior angle of Hexagon = 360/6.
(60)
Interior angle of Hexagon = 180 - exterior.
(120)
(180 - interior) / 2
(Base angles in an isosceles triangle are equal)
(30)
What steps are needed to find y?
Find Exterior angle of Hexagon.
Find Exterior angle of Octagon.
Find Interior angle of Hexagon.
Find Interior angle of Octagon.
360 subtract sum of both interior angles
