Question

If the middle points of the sides BC, CA and AB of the triangle ABC be (1, 3), (5, 7) and (– 5, 7), then the equation of the side AB is.

• A. $x - y - 2 = 0$
• B. $x - y + 12 = 0$
• C. $x + y - 12 = 0$
• D. None of these

Answer 1

Answer: (B)

$x - y + 12 = 0$

Answer 2

Slope of $D E = \frac { 7 - 3 } { 5 - 1 } = 1 \Rightarrow$ Slope of AB = 1

Hence equation of AB is $y - 7 = ( x + 5 ) \Rightarrow x - y + 12 = 0$ .