Question 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.