2-dimensional (2D) shapes have only two dimensions, length and width.
Here are some basic regular 2D Shapes :
A rectangle has 4 sides (quadrilateral) and 4 right angles, its opposite sides are equal, and they are parallel to each other and it has 2 lines of symmetry and rotational symmetry order 2.
To calculate the area of a rectangle, multiply its length by its width (The answer will be a square measure, for example: cm2)
To calculate the perimeter of a rectangle, add up the length of all sides.
A Square has 4 equal sides (quadrilateral) and 4 right angles, it has 2 pairs of parallel sides, it has 4 lines of symmetry and 4 rotational symmetry.
To calculate the area of a square, multiply its length by its width (The answer will be a square measure, for example: cm2)
To calculate the perimeter of a rectangle, add up the length of all sides or you can multiply the length of one side by 4 as the length of all sides equal.
A circle has no sides and no angles -as you see.
All points on the edge of the circle are at the same distance from the centre.
A circle has infinite number of line of symmetry and infinite order of rotational symmetry.
The distance from the centre to the all point on the edge called radius (plural : radii) and the whole line from edge to another called diameter.
To find out the diameter of a circle just double the radius (radius * 2)
The perimeter of a circle called “circumference” which is the whole line around the circle.
To find out the circumference of a circle we use this formula : C = π d
π = 22/7 ≈ 3.14
d = The diameter of the circle
A parallelogram has 4 sides (quadrilateral) 4 angles, its opposite sides are equal and they are parallel to each other, the opposite angles of a parallelogram are of equal measure, it has 2 lines of symmetry and rotational symmetry order 2.
The difference between a parallelogram and a rectangle is that a rectangle has 4 right angles but a parallelogram has opposite equal angles but not right angles.
There are more than one type from triangles this one in the picture is an Equilateral Triangle, it has 3 equal-sides and 3 equal-angles, the bottom side called “the base”
To find out the area of a triangle you multiply the perpendicular height, which is the line from the meddle of the base to the top angle, by length of the base and then divide by 2 .