# FORMULAS FOR SHAPES

## Circle

Formulas :

Area of circle  =  Πr2

Circumference of circle  =  2Πr

Example problems of area of circle

Example problems of circumference of circle

## Semicircle

Formulas :

Area of semicircle  =  Πr2 / 2

Circumference of circle  =  Πr

Example problems on semi circle

Formulas :

Area of quadrant  =  Πr/ 4

## Equilateral Triangle

Formulas :

Area of equilateral triangle  =  (√3/4)a2

Perimeter of equilateral triangle  =  3a

Example problems on equilateral triangle

## Scalene Triangle

Formulas :

Area of scalene triangle  =  √[s(s-a)(s-b)(s-c)]

Perimeter of scalene triangle  =  a + b +  c

Example problems on scalene triangle

## Parallelogram

Formulas :

Area of parallelogram  =  b x h

Perimeter of parallelogram =  2(a + b)

Example problems of perimeter of parallelogram

Formulas :

Area of quadrilateral  =  (1/2) x d x (h+ h2)

Perimeter of quadrilateral  =  a + b + c + d

Example problems of area of quadrilateral

## Rectangle

Formulas :

Area of rectangle  =  l x w

Perimeter of rectangle  =  2(l + w)

Examples problems on area of rectangle

Examples of perimeter of rectangle

## Square

Formulas :

Area of square  =  a x a

Perimeter of square  =  4a

Examples problems on area of square

Examples problems on perimeter of square

## Rhombus

Formulas :

Area of rhombus  =  (d1 x d2) / 2

Perimeter of rhombus  =  4a

Examples problems on perimeter of rhombus

## Trapezoid

Formulas :

Area of trapezoid  =  h(a + b) / 2

Perimeter of trapezoid  =  a + b + c + d

Examples problems on area of trapezoid

## Sector

Formulas :

Length of arc (l)  = (θ/360)  2Πr

When we know the radius "r" of the circle and central angle "θ" of the sector :

Area of the sector  =  (θ/360°⋅ Π r2

When we know the radius "r" of the circle and arc length "l"

Area of the sector = (l ⋅ r) / 2

Worksheet for length of arc

Area of sector worksheet

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