Question

Circumcentre of the triangle formed by the line $y = x,\mspace{6mu}\mspace{6mu} y = 2x$ and $y = 3x + 4$is.

• A. (6, 8)
• B. (6, – 8)
• C. (3, 4)
• D. (– 3, – 4)

Answer 1

Answer: (B)

(6, – 8)

Answer 2

$x ^ { 2 } + y ^ { 2 } = ( x + 4 ) ^ { 2 } + ( y + 8 ) ^ { 2 } \Rightarrow 8 x + 16 y + 80 = 0$

and $x ^ { 2 } + y ^ { 2 } = ( x + 2 ) ^ { 2 } + ( y + 2 ) ^ { 2 } \Rightarrow 4 x + 4 y + 8 = 0$

On simplification, we get $y = - 8$ and $x = 6$ .