Hi, It is well simples:
The distance between two points is :
d( A, B) = √[ (xb - xa)^2+(yb - ya)^2+(zb - za)^2]
Then,
A = (xa, ya, za )
B = (xb , yb , zb)
We know:
A = ( 2 ,0 ,-2)
And,
B = (5 , -4 , 6)
___________
xb - xa = 5-2 <=> 3
yb - ya = -4 - 0 <=> -4
zb - za = 6 - (-2) <=> 8
Then us stay:
d( A, B) = √[ (3)^2 + (-4)^2+(8)^2]
= √( 9 + 16 + 64)
= √( 25 + 64)
= √(89)
