A circle is a closed 2d figure in which the set of all the points in the plane is equidistant from a given point called the “Center”.
The distance from the Center to the outer line of the circle is called a radius.
Area of a Circle = πr²
Radius (r) = (Diameter)/2
Diameter (d) = 2 × radius
Circumference of a circle = 2πr
A triangle is a three-sided polygon (2d Shape) that has three edges and three vertices.
The sum of all the three angles of a triangle is equal to 180°.
Area of a triangle = 1/2 × base × height
Perimeter = a + b + c
(where a, b, and c are the sides of a triangle)
A square is a four-sided polygon (2d Shape), whose four sides are equal in length and all the angles are equal to 90°.
It is considered to be a two-dimensional regular quadrilateral.
The diagonals of the square also bisect each other at 90°.
Area of a Square = a^{2}
(where a is the side of a square)
Area of a square using diagonals = 1/2 × d^{2}
Perimeter of a square = 4 side
Perimeter of a square using diagonals = 2√2 × d
A rectangle is a 2d shape that has four sides, where the opposite sides are equal and parallel to each other.
All the angles of a rectangle are equal to 90°.
Area of a Rectangle = Length × width
Perimeter = 2(Length + Width)
A parallelogram is a two-dimensional geometrical shape, whose sides are parallel to each other.
It is a type of polygon having four sides (also called quadrilateral), where the pair of parallel sides are equal in length.
The Sum of adjacent angles of a parallelogram is equal to 180 degrees.
Area of a parallelogram = Base x height
Height = Area / Base
Base = Area / Height
Perimeter of a parallelogram = 2(a + b)
(where a and b are the sides)
A rhombus is a 2D shape with four straight, equal sides with both pairs of opposite sides being parallel.
The total distance travelled along the border of a rhombus is the perimeter of a rhombus.
Area of a rhombus = 1/2 × d_{1} × d_{2}
(Where d_{1 }and d_{2 }are the diagonals of the rhombus)
Perimeter of a rhombus = 4a
(where a is the length of the side of the rhombus)
What is trapezium ?
A trapezium is a quadrilateral which has a pair of parallel opposite sides.
Definition of kite :
A kite is a quadrilateral which has two pairs of adjacent sides equal in length.
What is polygon ?
A polygon can be defined as a flat or plane, two-dimensional closed shape with straight sides. It does not have curved sides.
Regular polygon :
A polygon having equal sides and equal angles is a regular polygon.
To find area of regular polygon, we use the formula
What is Apothem ?
A line from the center of a regular polygon at right angles to any of its sides.
Number of sides 3 4 5 6 7 8 9 10 |
Name of the polygon Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Nonagon Decagon |
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