Question:

$ABC$ is a triangle $G$ is the centroid $ D$ is the mid- point of $BC$. If $A - (2, 3) $ and $G = (7, 5)$, then the point $D$ is

Updated On: Jun 10, 2024
  • $ \left(\frac {19}{2},6\right)$
  • $ \left(\frac {9}{2},4\right)$
  • $\left(8, \frac{13}{2}\right)$
  • $ \left(\frac {11}{2},\frac{11}{2}\right)$
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The Correct Option is A

Solution and Explanation

Since, D is the mid point of BC. So, coordinate of
$BC$ are $\left(\frac{x_{2} + x_{3} }{2} , \frac{y_{2} +y_{3}}{2}\right)$
Given, $G (7, 5)$ is the centroid of $\Delta \,ABC $
$ \therefore 7 = \frac{2+ x_{2} + x_{3}}{3}$
and $5 = \frac{3+y_{2} + y_{3}}{3} $
$\Rightarrow x_{2} + x_{3} = 21-2$
and $ y_{2} + y_{3} = 15 -3 $
$ \Rightarrow x_{2} + x_{3} = 19$
and $ y_{2 } +y_{3} = 12 $
$ \Rightarrow \frac{x_{2} +x_{3}}{2} = \frac{19}{2}$
and $ \frac{y_{2} + y_{3} }{2} = 6 $
$\therefore$ Coordinate of D are $\left( \frac{19}{2} , 6 \right)$
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Concepts Used:

Straight lines

A straight line is a line having the shortest distance between two points. 

A straight line can be represented as an equation in various forms,  as show in the image below:

 

The following are the many forms of the equation of the line that are presented in straight line-

1. Slope – Point Form

Assume P0(x0, y0) is a fixed point on a non-vertical line L with m as its slope. If P (x, y) is an arbitrary point on L, then the point (x, y) lies on the line with slope m through the fixed point (x0, y0) if and only if its coordinates fulfil the equation below.

y – y0 = m (x – x0)

2. Two – Point Form

Let's look at the line. L crosses between two places. P1(x1, y1) and P2(x2, y2)  are general points on L, while P (x, y) is a general point on L. As a result, the three points P1, P2, and P are collinear, and it becomes

The slope of P2P = The slope of P1P2 , i.e.

\(\frac{y-y_1}{x-x_1} = \frac{y_2-y_1}{x_2-x_1}\)

Hence, the equation becomes:

y - y1 =\( \frac{y_2-y_1}{x_2-x_1} (x-x1)\)

3. Slope-Intercept Form

Assume that a line L with slope m intersects the y-axis at a distance c from the origin, and that the distance c is referred to as the line L's y-intercept. As a result, the coordinates of the spot on the y-axis where the line intersects are (0, c). As a result, the slope of the line L is m, and it passes through a fixed point (0, c). The equation of the line L thus obtained from the slope – point form is given by

y – c =m( x - 0 )

As a result, the point (x, y) on the line with slope m and y-intercept c lies on the line, if and only if

y = m x +c