Pythagoras was a Greek mathematician
who was born approximately 2700
years ago. He was responsible for
figuring out a lot of modern maths,
especially geometry and trigonometry.
Pythagoras came up with a rule to work out the
sides of a right angled triangle.
The rule only works for right angled triangles.
To use the rule you need 2 sides.
The rule says that if you square each of the two
short sides of a triangle then add them together
it will equal the square of the long side.
Short
Long
Short
c
a
b
2
2
a +b =c
2
long
short
short
2
2
short + short = long
2
1.
2.
3.
Square both short sides
Add the squares together
Square-root your answer
3
32 = 9
42 = 16
16 + 9 = 25
Square root of 25 = 5
x
4
9
92 = 81
122 = 144
81 + 144 = 225
Square root of 225 = 15
x
12
1.
2.
3.
4.
Square the long side
Square the short side
Subtract the short square from the long
square
Square-root your answer
a
202 = 400
162 = 256
400 - 256 = 144
Square root of 144 = 12
20
16
a
14
11
142 = 196
112 = 121
196- 121 = 75
Square root of 75 = 8.7 (1dp)
1.
2.
3.
Pythagoras's rule can be used to find the
last side of a right angled triangle.
The first step is to square the sides.
Then:
a) if they are both short sides add them.
b) or take the short side away from the long.
4.
Then square root your answer.
4.5
x
6
4.52 = 20.25
62 = 36
20.25 + 36 = 56.25
Square root of 56.25 = 7.5
a
20
7
92 = 81
72 = 49
81 - 49 = 32
Square root of 32 = 5.7
16
9