sure..its dere for us in add. math
maybe its for maths too..
the distance between 2 points is
Use the graphical method...
It's the Pythagoras' Theorem.
Draw any inclined line on a Cartesian Plane.
I have attached a file to this post. Refer to it.
Let A (x, y) and B(x1, y1).
To find the distance between A and B, i.e, the bold black inclined line, you will need to find the length of the two red dotted lines I have named x and y.
Using Pythagoras' Theorem,
Square of longest side = Sum of squares of the two smallest sides.
Send square to the other side...
>>> Longest side= Sq. root of the sum.
And to find the two smallest sides:
x = 3 - 0 [y1 - y]
y = 3 - 0 [x1 - x]
Note that the triangle formed is a right-angled one.
And now substituting the values for x and y, you will come back to the distance formula given.
Actually, this formula is just another way of using the Pythagoras' Theorem.
Am sorry, my explanation is quick... I have exams... If you want, I can be more explicit after the exams...LOL
Good Luck!