Find the third vertex of a triangle, if two of its vertices are at (−3, 1) and (0, −2) and the centroid is at the origin.
We have to find the co-ordinates of the third vertex of the given triangle. Let the co-ordinates of the third vertex be.
The co-ordinates of other two vertices are (−3, 1) and (0, −2)
The co-ordinate of the centroid is (0, 0)
We know that the co-ordinates of the centroid of a triangle whose vertices are $\left(x_{1}, y_{1}\right),\left(x_{2}, y_{2}\right),\left(x_{3}, y_{2}\right)$ is-
$\left(\frac{x_{1}+x_{2}+x_{3}}{3}, \frac{y_{1}+y_{2}+y_{3}}{3}\right)$
So,
$(0,0)=\left(\frac{x+0-3}{3}, \frac{y+1-2}{3}\right)$
Compare individual terms on both the sides-
$\frac{x-3}{3}=0$
So,
$x=3$
Similarly,
$\frac{y-1}{3}=0$
So,
$y=1$
So the co-ordinate of third vertex $(3,1)$