1
a

5

b

10

2
a

3 2 + 4 2 = 25
afstand = 25 = 5

b

afstand = 1 2 + 4 2 = 17

c

afstand = 14 2 + 14 2 = 392

3
a


b
c

A B 2 = 2 2 + 6 2 = 40 , dus A B = 40
B C 2 = 3 2 + 1 2 = 10 , dus B C = 10
A C 2 = 1 2 + 7 2 = 50 , dus A C = 50

d

A B 2 = B C 2 = 40 + 10 = 50 ; A C 2 = 50
Dus A B 2 + B C 2 = A C 2 .
Dus hoek A B C is recht.