A right triangle has one angle equal to 90 degrees. A right triangle can also be an isosceles triangle--which means that it has two sides that are equal. A right isosceles triangle has a 90-degree angle and two 45-degree angles. This is the only right triangle that is an isosceles triangle. But the answer is right triangle
By definition, we have
So, we have to solve two different equations, depending of the possible range for the variable. We have to remember about these ranges when we decide to accept or discard the solutions:
Suppose that 
In this case, the absolute value doesn't do anything: the equation is
We are supposing 
, so we can accept this solution.
Now, suppose that 
. Now the sign of the expression is flipped by the absolute value, and the equation becomes
Again, the solution is coherent with the assumption, so we can accept this value as well.
Answer:
The correct option is 4.
4) Doing two distance formulas to show that adjacent sides are not the same length.
Step-by-step explanation:
Parallelogram is a quadrilateral which has opposite sides equals and parallel. Example of a parallelogram are rhombus, rectangle, square etc.
We can prove that a quadrilateral MNOP is a parallelogram. If we find the slopes of all four sides and compare those of the opposite ends, same slopes would indicate the opposite sides are parallel, hence the quarilateral is a parallelogram. We can also find the distance of two opposing sides, and slopes of twp opposing sides to determine whether it is a parallelogram or not. The most difficult approach is that diagonals bisect each other at same point.
However, using only two distance formulas will not give us enough information to determine whether a side is parallel or not.
