X Y PLANES

In co-ordinate geometry, there is this "distance formula" that goes " Distance between P(x1,y1) and Q(x2,y2) on a 2-dimensional plane is given by sqrt[(x1-x2)^2 + (y1-y2)^2]"
What that means, is:
Let's call the 1st point "P".It has the co-ordinates (11,-4) .These are the values of "x1, and y1"
Let the 2nd point be "Q".It has co-ordinates (11,4), which we can take as "x2 and y2"
Applying distance formula,

Distance = sqrt[(11-11)^2 + (4-(-4))^2]
=sqrt[0^2 + (4 + 4)^2]
=sqrt[8^2]
=8 [sqrt cancels the "square" of 8 squared]

You can do the next one..
hope this helped

sorry about this, but if u see properly, u might have noticed that I interchanged the values when I substituted in the formula, i.e I took "y2-y1" instead of "y1-y2". But, as u may know, when u reverse the subtraction of 2 numbers, u just get the negative answer, the absolute number isn't changed. So, "x-y" = -"y-x". But, in the formula, these terms are squared, and whether they are negative or positive, their squares are the same.