1. How does the distance formula help me know if two or three sides of a triangle are equal?

If we consider what the distance formula really tells you, we can see the similarities. It is more than just a similar form.
The distance formula is commonly seen as:
D= √(x1−x2)2+(y1−y2)2
We commonly write the Pythagorean Theorem as:
c= √a2+b2
Consider the following major points (in Euclidean geometry on a Cartesian coordinate axis):
The definition of a distance from
x
to ±c is |x−c|
.
There is the relationship where
√(x−c)2=|x−c|=x−c
AND −x+c
The distance from one point to another is the definition of a line segment.
Any diagonal line segment has an
x
component and a
y
component, due to the fact that a slope is
Δy/Δx
. The greater the
y
contribution, the steeper the slope. The greater the
x
contribution, the flatter the slope.
What do you see in these formulas? Have you ever tried drawing a triangle on a Cartesian coordinate system? If so, you should see that these are two formulas relating the diagonal distance on a right triangle that is composed of two component distances
x
and
y
.
Or, we could put it another way through substitutions based on the distance definitions above. Let:
x1−x2=±ay1−y2=±b

(depending on if x1>x2 or x1