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The magnitude, or size, of a vector a\underline{i}+b\underline{j} in 2 dimensions is found by the formula: \sqrt{(a^2+b^2)}
The magnitude, or size, of a vector a\underline{i}+b\underline{j}+c\underline{k} in 3 dimensions is found by the formula: \sqrt{(a^2+b^2+c^2)}

## Summary/Background

The formula for the magnitude of a vector is basically Pythagoras' theorem extended to 3 dimensions.

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## Glossary

### magnitude

A measure of the size of a mathematical object

### union

The union of two sets A and B is the set containing all the elements of A and B.

### vector

A mathematical object with magnitude and direction.

Full Glossary List

## This question appears in the following syllabi:

SyllabusModuleSectionTopicExam Year
AQA A-Level (UK - Pre-2017)C4VectorsVector algebra-
CCEA A-Level (NI)C4VectorsVector algebra-
Edexcel A-Level (UK - Pre-2017)C4VectorsVector algebra-
I.B. Higher Level4VectorsVector algebra-
I.B. Standard Level4VectorsVector algebra-
OCR A-Level (UK - Pre-2017)C4VectorsVector algebra-
OCR-MEI A-Level (UK - Pre-2017)C4VectorsVector algebra-
Scottish HighersM3VectorsVector algebra-
WJEC A-Level (Wales)C4VectorsVector algebra-
Methods (UK)M4VectorsVector algebra-
CIE A-Level (UK)P1VectorsVector algebra-
Pre-U A-Level (UK)6VectorsVector algebra-