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| 2d Shapes Polygons and More |
2d Shapes Polygons and More
'2D' stands for 2-dimensional. A 2D shape is any shape that has two dimensions. Think about what it means to have two dimensions for a moment. If we had only one dimension to work with, we could only move backwards or forwards in a line. A line is one-dimensional. If we had two dimensions, on the other hand, we could go forwards and backwards in a line and turn in any direction to start a new line. We are essentially able to travel anywhere on a flat surface. In mathematics, a flat surface is called a plane. A plane is one example of a two-dimensional shape. A plane is essentially the largest sheet of paper you will ever find. In fact, it is a sheet of paper so large that it never ends. One way of thinking about 2D shapes is anything that lays flat on a piece of paper.
Any n-sided figure, which can be perfectly and wholly traced on a plane is a 2D figure or polygon. This means any figure having all points on a single plane is a planar figure. Some examples are
Rectangle
Number of sides - 4 Special Info- Has four sides, with opposite sides parallel and adjacent sides of same or unequal length(a and b) All internal angles are 90 degrees Sum of all internal angles in 360 degrees Diagonals are mutually perpendicular and bisect one another
Area - a * b Perimeter - 2(a+b)
Square
Number of sides - 4 Special Info- Has four sides, with opposite sides parallel and all sides of same length (a) All internal angles are 90 degrees Sum of all internal angles in 360 degrees Diagonals are mutually perpendicular and bisect one another
Area - 1/2(base Perimeter - 4a
Triangle
Number of sides - 3 Special Info- Has a height which is the perpendicular distance from a vertex to the opposite side(base), can lie inside or outside the triangle Sum of all angles is 180 degrees
Area - 1/2(base * height)
Circle
Number of sides - Infinite (A polygon with infinite number of sides is a circle) Special Info- Angle through center in 360 Always defined from a point known as center of circle Perpendicular distance from the center to a point on periphery is called the radius(r) Any line passing through the circle and touching the periphery at both ends is called a chord Chord passing through the center of the circle is diameter
Area - {pi} * r * r Perimeter - 2 * {pi} * r