# Area and Perimeter of Shapes Tricks and Formulas

**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**

**Area of the ellipse**

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