# Area and Perimeter of Shapes Tricks and Formulas

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## Pythagoras Theorem

For right triangle ABC

For acute triangle ABC

For obtuse triangle ABC

## Area of Triangle

### When Lengths of the Sides Are Given

### When Lengths of the Base and Altitude Are Given

### When Lengths of Two Sides and the Included Angle Are Given

### For Equilateral Triangle

### For Isosceles Triangle

## Apollos Theorem

If AD is the median, then:

## Angle Bisector Theorem

If AD is the angle bisector for angle A, then:

## Area of Quadrilateral

### For Cyclic Quadrilateral

### If Lengths of One Diagonal and Two Offsets Are Given

### If Lengths of Two Diagonals and the Included Angle Are Given

### For Trapezium

### For Parallelogram

### For Rhombus

The halves of diagonals and a side of a rhombus form a right angled triangle with side as the hypotenuse.

### For Rectangle

Perimeter of a rectangle

**For Square**

Area of a square

Area of 4 walls of a room

## Polygons

### Number of Diagonals

### The Sum of All the Interior Angles

### The Sum of All the Exterior Angles

## Area of Regular Hexagon

Area=

## Circle

### Circumference

### Area

### Length of Arc

### Area of Sector

Or

### Perimeter of Sector

## Ellipse

If semi-major axis and semi-minor axis

### Perimeter of the Ellipse