## Area & Perimeter

## Triangle

Area of a triangle = 1/2 * base * height

## Scalene Triangle

**1. Perimeter of a triangle = a + b + c**

**2. Area of a triangle**

## Right Angled Triangle

**1. Perimeter of right angled triangle = p+b+h**

**2. Area of right angled triangle= 1/2 X base x perpendicular**

## Isosceles Triangle

**1. Perimeter of Isosceles Triangle = 2b+a**

**2. Area of Isosceles Triangle =**

## Equilateral Triangle

**1. Perimeter of equilateral triangle = 3a**

**2. Area of equilateral triangle**

**3. Height of equilateral triangle**

## Rectangle

#### 1. Area of Rectangle

Area = length X breath= ab

#### 2. Perimeter of Rectangle

Perimeter = 2(length+breath)= 2(a+b)

#### 3. Diagonal of Rectangle

## Square

#### 1. Area of Square

Area = (side)

^{2}=a^{2}#### 2. Perimeter of Square

Perimeter = 4 X Side = 4a

#### 3. Diagonal of Square

#### 4. Area of Square in term of diagonal

## Parallelogram

1. Area of Parallelogram =

**base X height**=**b X h**2. Perimeter of Parallelogram =

**2 (base X height)**=**2 (b X h)**## Rhombus

1. Area of Rhombus =

**1/2 X d**_{1}X d_{2}2. One Side of Rhombus =

3. Perimeter of Rhombus =

**4 X side**4.

**4a**^{2}= d^{2}_{1}+ d^{2}_{2}## Trapezium

## Quadrilateral

Area of Quadrilateral= 1/2 X AC X (BN +DM)

## Polygon

## Circle

#### 1. Area of Circle = πr^{2}

^{}

#### 2. Circumference of circle = 2πr

#### 3. Diameter of Circle = 2r

#### 4. Length of an arc of a circle

#### 5. Area of sector of a circle

## Circular Ring

Area of Circular Ring = π(R^{2}-r^{2})

#### Note:

1. Radius of incircle of an equilateral triangle whose side is a, is

and area of incircle is

2. Radius of circumcircle of an equilateral triangle whose side is a, is

and area of circumcircle is

3. Area of four walls of a room = 2(length+breadth) X height

4. If the Parameter of square and rectangle are same, then area of square is always greater than the area of rectangle.

5. If ratio of areas of two squares is A1:A2, the ratio of their parameters is

6. Each diagonal of a parallelogram divides parallelogram into two triangle of same area.

7. Diagonals of rhombus bisect each other at right angle.

8. If four circle of radius r touches each other externally,

then the bounded area between them is

9. If the length and breadth of a rectangle are a and b respectively. Then the radius and area of a circle whose radius is maximum is

where a>b

10. If each side of a figure is being n times, then the area is being

11. On changing each side of a figure by x%, then its area changed by