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 2D add and subtract

2 2D add and subtract 2

3 3D add and subtract

4 Magnitude 4

5 Multiplication by a scalar 2

6 Distance between two points

7 Unit vectors

8 Unit vectors 2

9 Unit vectors 3

10 Equations of lines

11 Equations of lines 2

12 Equations of lines 3

13 Equations of lines 4

14 Equations of lines 5

15 Intersecting lines

16 Intersection with a circle

17 Scalar product

18 Vector to cartesian form

19 Angle between vectors

20 Angle between vectors 2

21 Angle between 2D lines

22 Angle between 2D lines 2

23 Angle between 3D lines

24 Area of a triangle

25 Area of a triangle 2

26 Perpendicular vectors

27 Perpendicular vectors 2

28 Perpendicular vectors 3

29 Perpendicular vectors 4

30 Perpendicular lines

31 Perpendicular lines 2

32 Foot of perpendicular

33 Collinear points

34 Memorise the formulae

35 Diagonals of a parallelogram

36 Extended problem 1

37 Extended problem 2

38 Sequence O-test

39 O-test 1

40 O-test 2

41 O-test 3

42 O-test 4

43 O-test 5

44 O-test 6

45 O-test 7

46 O-test 8

47 Exam O-test 1

48 Exam O-test 2

49 Exam O-test 3

50 Exam O-test 4

51 Exam O-test 5

52 Exam timed O-test

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