if (2,-1),(p,5)and (p-3,4) are collinear points . find p.

Asked by kissi_1995 | 21st Jul, 2009, 07:08: PM

Expert Answer:

If  three  points are collinear then

x1(y2 -y3) +x2(y3 -y1) +x3(y1 -y2) =0

A(2,-1) :B (p ,5) C (p-3 ,4)

2(5 -4) +p[4-(-1)] +p-3(-1 -5) =0  [solving this eq] .......I

2 +5p -6p +18 =0

-p +20 =0

p =20Ans ( substitute the value of p in the above equation  I to  check )

Answered by  | 22nd Jul, 2009, 12:37: PM

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