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Coordinate Geometry

Question
CBSEENMA10009676

In what ratio does the x-y-2=0 divided the line segment joining the points A(3,-1) and B(8,9)?

Solution

let t line x-y-2=0 divid t line segment in t ratio k : 1 at point C
so coordinates of C are

open parentheses fraction numerator 8 straight k plus 3 over denominator straight k plus 1 end fraction close parentheses comma open parentheses fraction numerator 9 straight k minus 1 over denominator straight k plus 1 end fraction close parentheses

C lies on x - y - 2 = o

so, subs coordinates of x,y in tis eq.
open parentheses fraction numerator 8 straight k plus 3 over denominator straight k plus 1 end fraction close parentheses minus open parentheses fraction numerator 9 straight k minus 1 over denominator straight k plus 1 end fraction close parentheses space minus 2 space equals 0
fraction numerator 8 k plus 3 minus 9 k plus 1 minus 2 k minus 2 over denominator k plus 1 end fraction space equals 0
fraction numerator 8 k plus 3 minus 9 k plus 1 minus 2 k minus 2 over denominator k plus 1 end fraction space equals space 0
fraction numerator negative 3 k plus 2 over denominator k plus 1 end fraction space equals space 0
minus 3 k space plus 2 space equals space 0
rightwards double arrow space k space equals space 2 divided by 3
i. e space 2 colon 3