Since AB is perpendicular to
AC
Then the product of the slopes =
-1
Let m1 be the slope for
AB:
==> m1= (-2-3)/(4-1) =
-5/3
Let m2 be the slope for
CD
==> m1*m2 =
-1
==> -5/3 *m2 =
-1
==: m2 = 3/5
but m2 =
(y-1)/(x-6) = 3/5
==> y-1 =
(3/5)(x-6)
==> y= (3/5)(x-6) +
1
=> y= (3/5)x - 18/5 +
5/5
==> y= (3/5)x -
13/5
Therfore , we need x, y alues that verifies the
equation,
Let us substitute the
choices:
A( 1, -2)
==>
y= (3/5)*1 - 13/5
= 3/5 - 13/5 = -10/5 =
-2
The point (1, -2) verifies the
equation.
Then D = (1,
-2)
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