Question

If ABCD is a square having coordinates A (4, 5), B (4, 1) and C (8, 1), the coordinates of D are

• A. (4,8)
• B. (8,4)
• C. (8,5)
• D. (8,6)

Answer 1

The correct option is C

(8,5)

If ABCD is a square the midpoints of the diagonals will be same.

So midpoints of AC and BD is the same.

Midpoint of the line joining two points A (x${}_{1,}$y${}_1$) and B (x${}_{2,}$y${}_2$) is ($\frac{x_1+x_2}{2}$, $\frac{y_1+y_2}{2}$)

Midpoint of AC is (6, 3).

Midpoint of BD is also the same.

So using the above formula we get the coordinates of D as (8, 5).