In what ratio does the point P(−4, y) divides the line segment joining the points A(−6, 10) and B(3, −8)? Hence find the value of y.
Solution
Let P divides the line segment AB in the ratio k : 1
Using section formula
x = `(m_1x_2 + m_2x_1)/(m_1+m_2), y = (m_1y_2 + m_2y_1)/(m_1+m_2)`
A(-6, 10) and B(3, 8)
m1 : m2 = k : 1
plugging values in the formula we get
- 4 = `( k xx 3 + 1 xx (-6))/(k + 1), y = ( k xx (- 8) + 1 xx 10)/(k + 1)`
- 4 = `( 3k - 6)/(k + 1), y = (-8k + 10)/(k + 1)`
Considering only x coordinate to find the value of k
- 4k - 4 = 3k - 6
- 7k = - 2
k = `2/7`
k : 1 = 2 : 7
Now, we have to find the value of y
so, we will use section formula only in y coordinate to find the value of y.
y = `(2 xx (- 8) + 7 xx 10)/(2 + 7)`
y = `( - 16 + 70 )/(9)`
y = 6
Therefore, P divides the line segment AB in 2 : 7 ratio
And value of y is 6.