Welcome to the Math Salamanders' Geometry Formula Sheet area.
Here you will find a range of different Geometry formulas for 2d and 3d shapes.
Here you will find our support page about different Geometry formulas, including triangles, circles, quadrilaterals and polygons, as well as 3d shapes.
Using these sheets will help your child to:
Quicklinks to ...
Angles in a triangle

Angles in a triangle add up to 180°\[ a + b + c = 180^o \] 
Angles on a straight line

Angles on a straight line add up to 180°\[ a + b = 180^o \] 
Angles around a point

Angles around a point add up to 360°\[ a + b + c + d + e = 360^o \] 
Convert Degrees to Radians

Convert from degrees (d) to radians (r)\[ r = {\pi \over 180 } d \] Convert from radians (r) to degrees (d)\[ d = {180 \over \pi } r \] Want to find out some more? 
Angles in a triangle

Angles in a triangle add up to 180°\[ a + b + c = 180^{\circ } \] 
Area of a triangle

Area of a triangle\[ A = {1 \over 2} \times b \times h = { 1\over 2} bh \; or \; {bh \over 2} \] where b is the length of the base of the triangle and h is the perpendicular height. 
Pythagoras' Theorem

Pythagoras' theorem\[ a^2 + b^2 = c^2 \] where a,b and c are the sides of a right triangle. Side c is the hypotenuse (longest side). Pythagoras Theorem Worksheets 
Triangle Trigonometry  sine, cosine and tangent

Basic triangle trigonometry\[ sin (\theta) = {o \over h} \] \[ cos (\theta) = {a \over h} \] \[ tan (\theta) = {o \over a} \] 
The Sine and Cosine Rules

The Sine rule\[ {a \over sin(A)} = {b \over sin(B)} = {c \over sin(C)} \] The Cosine rule\[ a^2 = b^2 + c^2  2bc \cdot cos(A) \]

For more Geometry formulas about triangles, including examples showing the sine and cosine rules, use the link below.
Angles in a quadrilateral

Angles in a quadrilateral add up to 360°\[ a + b + c + d = 360^o \] a + b + c + d = 360° 
Angles in a rectangle

Angles in a rectangle are all right angles (equal to 90°). 
Area and Perimeter of a rectangle

Area of a rectangle\[ A = a \times b \; or \; a \cdot b \] Perimeter of a rectangle\[ P = 2a + 2b \] where a and b are the lengths of the two adjacent sides. Want to know some more? 
Angles in a parallelogram

Angles in a parallelogramopposide angles are equal (opposite sides are also equal). \[ a + b = 180^o \] 
Area of a parallelogram

Area of a parallelogram\[ A = b \times h \] where b is the length of the base, and h is the perpendicular height of the parallelogram. Want to find out some more? 
Circumference of a circleThe circumference of a circle is the distance all the way around the outside of the circle, or the perimeter of the circle. 
The Circumference of a circle\[ C = 2 \pi r \; or \; \pi d \] where r is the radius of the circle and d is the diameter of the circle. Find out some more: 
Area of a circle

The area of a circle\[ A = \pi r^2 \] where r is the radius of the circle. Find out some more: 
Length of an arc of a circle

The length L of an arc of a circle is:\[ L = { \theta \over 180} \cdot \pi r \] where θ is the angle (in degrees) and r is the radius. 
Area of a sector of a circle

The area A of a sector of a circle is: \[ A = { \theta \over 360} \cdot \pi r^2 \] where θ is the angle (in degrees) and r is the radius. Want to find out some more? 
Triangle along a semicircle

A triangle drawn inside a circle with one side going along the diameter, and the other 2 sides meeting at any point along the edge of the circle will always make a right angle. The triangle will always be a right triangle. 
Equilateral Triangle

Angle: 60° Interior angles add up to 180° \[ Area = { \sqrt 3 \over 4} s^2 \] \[ Perimeter = 3s \] 
Square

Angle: 90° Interior angles add up to 360° \[ Area = s^2 \] \[ Perimeter = 4s \] 
Pentagon

Angle: 108° Interior angles add up to 540° \[ Area = {1 \over 4} s^2 \sqrt {5(5 + 2 \sqrt 5)} \] \[ Perimeter = 5s \] 
Hexagon

Angle: 120° Interior angles add up to 720° \[ Area = {3 \sqrt {3} \over 2} s^2 \] \[ Perimeter = 6s \] 
Heptagon

Angle: 128.6° (to 1dp) Interior angles add up to 900° \[ Area = {7 \over 4} s^2 \cot ({180^{\circ} \over 7}) \] \[ Perimeter = 7s \] 
Octagon

Angle: 135° Interior angles add up to 1080° \[ Area = 2 s^2 (1 + \sqrt 2) \] \[ Perimeter = 8s \] 
Nonagon

Angle: 140° Interior angles add up to 1260° \[ Area = {9 \over 4} s^2 \cot {20^{\circ}} \] \[ Perimeter = 9s \] 
Decagon

Angle: 144° Interior angles add up to 1440° \[ Area = {5 \over 2} s^2 \sqrt {5 + 2 \sqrt 5} \] \[ Perimeter = 10s \] 
A general formula for this rule for an nsided regular polygon is:
Interior angles add up to \[ (n  2) \times 180^{\circ} \]
Each angle must be \[ {180 (n2)^{\circ} \over n} \]
A general formula for the area of a regular polygon with nside of length s is:
\[ A = {ns^2 \over 4 \tan ({180^{\circ} \over n})} \]
This can also be written: \[ A = {n \over 4 } s^2 \cot ({180 \over n})^{\circ} \]
For more support finding the area of regaular polygons, try our calculator:
A general formula for the perimeter of a regular polygon with nside of length s is:
\[ P = n \times s \]
Cubes

Volume of a cube:\[ V = a \times a \times a = a^3 \] Surface area of a cube:\[ A = 6a^2 \] where a is the length of each side. Want to find out some more? 
Cuboid

Volume of a cuboid:\[ V = l \times w \times h = lwh \] Surface area of a cuboid:\[ A = 2lw + 2wh + 2lh \] where l is the length, w is the width and h is the height of the cuboid. Looking for some more information? 
Sphere

Volume of a sphere:\[ V = {4 \over 3} \pi r^3 \] Surface area of a sphere:\[ A = 4 \pi r^2 \] where r is the radius of the sphere. Want some more information? 
Cylinder

Volume of a cylinder\[ V = \pi r^2 h \] Surface area of a closed cylinder:\[ A = 2 \pi r h + 2 \pi r^2 = 2 \pi r (r + h) \] Surface area of an open cylinder (a hollow tube):\[ A = 2 \pi r h \] where r is the radius of the cylinder and h is the height. Looking for more information? 
Cone

Volume of a cone\[ V = {1 \over 3} \pi r^2 h \] Surface area of a cone (including base):\[ A = \pi r^2 + \pi r s = \pi r (r + s) \] OR \[ A = \pi r (r + \sqrt {r^2 + h^2}) \] Surface area of a cone (excluding base):\[ A = \pi r s \] OR \[ A = \pi r \sqrt {r^2 + h^2} \] where r is the radius of the widest part of the cone, h is the height and s is the slant height of the cone. Want some more help? 
Square Pyramid

Volume of a square pyramid\[ V = {1 \over 3} b^2 h \] Surface area of a square pyramid (including base):\[ A = b^2 + 2 b s \] Surface area of a square pyramid (excluding base):\[ A = 2 b s \] where b is the length of one side of the base, h is the vertical height of the pyramid and s is the slant height of one of the triangles. Looking for more support? 
Pyramid (general)

Volume of any pyramid\[ {1 \over 3} A h \] where A is the area of the base, and h is the height. This formula works for any pyramid with a rectangular or triangular base and triangular sides. 
Take a look at some more of our worksheets similar to these.
Here you will find a range of geometry cheat sheets to help you answer a range of geometry questions.
The sheets contain information about angles, types and properties of 2d and 3d shapes, and also common formulas associated with 2d and 3d shapes.
Included in this page are:
Using the sheets in this section will help you understand and answer a range of geometry questions.
Here you will find a List of different Geometric Shapes.
Included with each shape is a small picture and a description of the properties the shape has and how it relates to other shapes.
Included in this page are the following shapes:
All the printable Geometry worksheets in this section support the Elementary Math Benchmarks.
Here you will find our range of Free Nets for 3D Shapes.
The following printables contain nets of common 3D shapes that your child should know. Each net sheet is available both with and without tabs to aid sticking together.
Using these sheets will help your child to:
Do you know the special geometric names to describe the different parts of a circle?
Well you can find all the support you need on this page, complete with some practice worksheets and an online quiz!
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