Friday, November 22, 2013

Find the equation of the line of slope -3/4 that forms with the coordinate axes a triangle which has the area of 24 square units.

First the form of the equation would
be;


y= mx + b, where m is the
slop.


==> y = (-3/4)x +
b


when x = 0, then y = (-3/4) 0 + b=
b


then the point where the line intersect with the y-axis
is (0,b)


when y = 0 , then (-3/4) x +b=
0


==> (3/4) x=
b


==> x= (4/3)b


then
the point where the line intersect with the x-axis is  (4b/3,
0)


but, the area of the triangle
is:


A= 1/2 * 4b/3 * b


24 = 1/2
* 4b/3 *b


24 = 1/2 * 4b^2/3 = 4b^2
/6


==> b^2 =
24*6/4


==> b^2 =
36


==> b = 6, -6


then
the eqution of teh slope is:


y = (-3/4) x + 6    and y=
(-3/4)x -6

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