Place the parallelogram in the coordinate plane with the right angle at the origin and one side each on the x- and y-axis.
See solution.
Practice makes perfect
We are asked to show the following statement.
Ifa parallelogram has one right angle,
thenit has four right angles.
We are asked to write a coordinate proof, so place the parallelogram in the coordinate plane.
It is helpful if you place the vertex with the given right angle at the origin and one vertex each on the x- and y-axis.
Since opposite sides of a parallelogram are parallel, this placement of the parallelogram guarantees that two sides are horizontal and two sides are vertical.
Since horizontal and vertical lines are perpendicular, all four angles of the parallelogram are right angles.
