1. c2 = a2 + b2 Pythagoras's Theorem c a b In any right angled triangle,
Label the longest side (the hypotenuse) as c. Label the two other (shorter) sides as a and b. Then…….. b a c
c2 = a2 + b2

2. a2 = c2 - b2 Pythagoras's Theorem c a b
If you wanted one of the two shorter sides, then
You can rearrange the formula…… b a c
a2 = c2 - b2

3. x = 10 cm x 6cm 8cm Example 1… Find x
As we are finding the hypotenuse, then use the version of the formula with the + sign.
8cm
6cm x
c2 = a2 + b2
x2 =
x2 =
x2 = 100
x = 100
x = 10 cm

4. Example 2… Find x
As we are finding a shorter side, then use the version of the formula with the - sign.
12cm x
17cm
a2 = c2 - b2
x2 =
x2 =
x2 = 145
x = 145
x = 12.1 cm