The magnitude of the vector AB is its length, which is found by using Pythagoras' theorem.
Software/Applets used on this page

Uses Cinderella interactive geometry
Glossary
magnitude
A measure of the size of a mathematical object
vector
A mathematical object with magnitude and direction.
This question appears in the following syllabi:
Syllabus | Module | Section | Topic | Exam Year |
---|---|---|---|---|
AQA A-Level (UK - Pre-2017) | C4 | Vectors | 2D Vector geometry | - |
CBSE XII (India) | Vectors and 3-D Geometry | Vectors | Vectors and scalars, magnitude and direction of a vector | - |
CCEA A-Level (NI) | C4 | Vectors | 2D Vector geometry | - |
CIE A-Level (UK) | P1 | Vectors | 2D Vector geometry | - |
Edexcel A-Level (UK - Pre-2017) | C4 | Vectors | 2D Vector geometry | - |
I.B. Higher Level | 4 | Vectors | 2D Vector geometry | - |
I.B. Standard Level | 4 | Vectors | 2D Vector geometry | - |
Methods (UK) | M4 | Vectors | 2D Vector geometry | - |
OCR A-Level (UK - Pre-2017) | C4 | Vectors | 2D Vector geometry | - |
OCR-MEI A-Level (UK - Pre-2017) | C4 | Vectors | 2D Vector geometry | - |
Pre-Calculus (US) | E1 | Vectors | 2D Vector geometry | - |
Pre-U A-Level (UK) | 6 | Vectors | 2D Vector geometry | - |
Scottish (Highers + Advanced) | HM3 | Vectors | 2D Vector geometry | - |
Scottish Highers | M3 | Vectors | 2D Vector geometry | - |
Universal (all site questions) | V | Vectors | 2D Vector geometry | - |
WJEC A-Level (Wales) | C4 | Vectors | 2D Vector geometry | - |