Question

If two vertices of a triangle are $(3,-5)$ and $(-7,8)$ and centroid lies at the point $(-1,1)$, third vertex of the triangle is at the point $(a,b)$ then

• A. $a+b=2$
• B. $a-b=2$
• C. $a+2b=2$
• D. $2a+b=2$

Answer 1

Answer: (D)

$2a+b=2$

$-1=\frac{3-7+a}{3}$ and $1=\frac{-5+8+b}{3}$
$\Rightarrow a=1$ and $b=0$
Hence $2a+b=2$