Geometry Basics Foundation

GCSEKS3Level 1-3AQACambridge iGCSEEdexcelEdexcel iGCSEOCRWJEC

Geometry Basics Foundation Revision

Geometry Basics: The 5 Simple Rules

Geometry basics will teach you the 5 simple rules needed to answer basic geometry questions, as well as give you the foundations to build as you work through the different geometry topics.

Having basic algebra knowledge is required to solve geometry problems.

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE
angles in a triangle 180 degrees

Angles in a triangle add up to 180\degree

angles in a triangle 180 degrees

The angles in a triangle add up to 180\degree

\textcolor{red}{a} + \textcolor{skyblue}{b} + \textcolor{green}{c} = 180\degree

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE
angles in a quadrilateral 360 degrees

Angles in a quadrilateral add up to 360\degree

angles in a quadrilateral 360 degrees

The angles in a quadrilateral (4 sided shape) add up to 360\degree

\textcolor{red}{a} + \textcolor{skyblue}{b} + \textcolor{green}{c} + \textcolor{yellow}{d}= 360\degree

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE

Angles on a straight line add up to 180\degree

The angles on a straight line all add up to 180\degree

\textcolor{red}{a} + \textcolor{skyblue}{b} + \textcolor{green}{c} = 180\degree

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE

Angles around a point add up to 360\degree

angles around a point 360 degrees

The angles around a point all add up to 360\degree

\textcolor{red}{a} + \textcolor{skyblue}{b} + \textcolor{green}{c} + \textcolor{yellow}{d}= 360\degree

Level 1-3GCSEKS3AQAEdexcelOCRWJEC

Two sides and two angles of an isosceles triangle are the same

base angles isosceles triangle equal
base angles isosceles triangle equal

The two sides marked with the lines are the same length.

The two base angles, \textcolor{red}{x}, are the same.

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE
Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE
unknown angle in triangle

Example 1: Angles in a Triangle

Find the value of x in the triangle shown:

[2 marks] 

unknown angle in triangle

We know that angles in a triangle add up to 180\degree,

40\degree + 80\degree + x\degree = 180\degree

x= 180\degree -40\degree - 80\degree = 60\degree

x= 60\degree

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE
unknown angle isosceles triangle

Example 2: Finding a Missing Angle

Find the value of x in the triangle shown:

[2 marks]

unknown angle isosceles triangle

We know that in an isosceles triangle, the base angles are equal.

This means we can form the equation:

x\degree + x\degree + 50\degree = 180\degree

2x\degree = 180\degree - 50\degree

2x = 130\degree

x\degree = 65\degree

Level 1-3GCSEKS3AQAEdexcelOCRWJECCambridge iGCSEEdexcel iGCSE

Geometry Basics Foundation Example Questions

Angles on a straight line all add together to make 180\degree

 

\begin{aligned}103\degree+\angle CDB &= 180\degree \\ \angle CDB &= 180\degree-103\degree = 77\degree \end{aligned}

MME Premium Laptop

Save your answers with

MME Premium

Gold Standard Education

Angles around a point all add together to make 360\degree

 

100\degree+50\degree+x\degree+105\degree =360\degree \\ x=360\degree-100\degree-105\degree-50\degree \\ x= 105\degree

MME Premium Laptop

Save your answers with

MME Premium

Gold Standard Education

Base angles in an isosceles triangle are equal and angles in a triangle add up to 180\degree

 

61\degree+61\degree+y\degree =180\degree \\ y\degree =180\degree-61\degree-61\degree \\ y=58\degree

MME Premium Laptop

Save your answers with

MME Premium

Gold Standard Education

Base angles in an isosceles triangle are equal and angles in a triangle add up to 180\degree

 

\begin{aligned}x+x+55\degree&=180\degree \\ 2x&=180\degree-55\degree = 125\degree  \\ x&=\dfrac{125\degree}{2}\end{aligned}

x=62.5\degree

MME Premium Laptop

Save your answers with

MME Premium

Gold Standard Education

Angles on a straight line all add together to make 180\degree so

 

x=180\degree-115\degree=65\degree

 

Angles in a triangle add up to 180\degree

 

y=180\degree-25\degree-65\degree

y=90\degree

MME Premium Laptop

Save your answers with

MME Premium

Gold Standard Education

Geometry Basics Foundation Worksheet and Example Questions

Site Logo

(NEW) Geometry Problems Foundation Exam Style Questions - MME

Level 1-3GCSENewOfficial MME

Geometry Basics Foundation Drill Questions

Site Logo

Angles - Drill Questions

Level 1-3GCSE
Site Logo

Geometry Problems - Drill Questions

Level 4-5GCSE
MME Premium

Gold Standard Education