Answer:
The co-ordinates of the top-right vertex are (3a, a)
Explanation:
Let's take "a" be the shorter side and "b" be the longer side.
Given: The longer side of the rectangle is 3 times it's shorter side.
So b = 3a.
The length of the rectangle which is x-coordinate 3a, and y-coordinate is a.
Therefore, the top-right vertex are (3a, a)
Thank you.