Question:

Let the circumcentre of a triangle with vertices A(a, 3), B(b, 5) and C(a, b), ab > 0 be P(1, 1). If the line AP intersects the line BC at the point Q(k1, k2), then k1 + k2 is equal to :

Updated On: Mar 15, 2025
  • 2
  • \(\frac{4}{7}\)
  • \(\frac{2}{7}\)
  • 4
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is B

Solution and Explanation

Triangle with Vertices
Let D be mid-point of AC, then
\(\begin{array}{l} \frac{b+3}{2}=1\Rightarrow b=-1\end{array}\)
Let E be mid-point of BC,
\(\begin{array}{l} \frac{5-b}{b-a}\cdot\frac{\frac{\left(3+b\right)}{2}}{\frac{a+b}{2}-1}=-1 \end{array}\)
On Putting b = –1, we get a = 5 or –3
But a = 5 is rejected as ab> 0
A(–3, 3), B(–1, 5), C(–3, –1), P(1, 1)
Line BC y = 3x + 8
\(\begin{array}{l}Line\ AP\Rightarrow y=\frac{3-x}{2}\end{array}\)
Point of intersection (-13/7, 17/7)
Then, \(k_1+k_2 = -\frac{13}{7}+\frac{17}{7} = \frac{4}{7}\)
Was this answer helpful?
8
14

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