5. In a classroom, 4 friends are seated at the points A, B, C and D as shown in Fig. 7.8. Champa and Chameli walk into the class and after observing for a few minutes Champa asks Chameli, “Don’t you think ABCD is a square?” Chameli disagrees. Using distance formula, find which of them is correct.
The coordinates of the points:
are the positions of 4 friends.
The distance between two points is given by:
Hence,
And the lengths of diagonals:
So, here it can be seen that all sides of quadrilateral ABCD are of the same lengths and diagonals are also having the same length.
Therefore, quadrilateral ABCD is a square and Champa is saying right.