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

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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)

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Area and Perimeter of Triangle

Angles and Sides of 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 = a2

(where a is the side of a square)

Area of a square using diagonals = 1/2 × d2

Perimeter of a square = 4 side

Perimeter of a square using diagonals = 2√2 × d

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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)

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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)

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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 × d1 × d2

(Where dand dare the diagonals of the rhombus)

Perimeter of a rhombus = 4a 

(where a is the length of the side of the rhombus)

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What is trapezium ?

A trapezium is a quadrilateral which has a pair of parallel opposite sides.

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Definition of kite :

A kite is a quadrilateral which has two pairs of adjacent sides equal in length.

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What is polygon ?

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 

Area of regular polygon = 12 × Perimeter × Apothem

What is Apothem ?

A line from the center of a regular polygon at right angles to any of its sides.

Number of sides









Name of the polygon









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