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**

More in this topic

1 Distance between two points

2 Exam Question

3 Exam Question

4 Magnitude 4

5 2D add and subtract

6 Exam Question

7 2D add and subtract 2

8 3D add and subtract

9 Exam Question

10 Multiplication by a scalar 2

11 Sequence O-test

12 Unit vectors 2

13 Unit vectors

14 The section formula

15 Unit vectors 3

16 Area of a triangle

17 Area of a triangle 2

18 Vector to cartesian form

19 Exam Question

20 Scalar product

21 Angle between vectors

22 Angle between vectors 2

23 O-test 1

24 O-test 2

25 Exam Question

26 Perpendicular vectors

27 Exam Question

28 Perpendicular vectors 2

29 Perpendicular vectors 3

30 Perpendicular vectors 4

31 Exam Question

32 Exam Question

33 Exam Question

34 Exam Question

35 Collinear points

36 Memorise the formulae

37 O-test 5

38 Diagonals of a parallelogram

39 O-test 6

40 O-test 7

41 O-test 8

42 Exam O-test 2

43 Exam O-test 4

44 Exam O-test 5