Question 840574
<pre>
{{{drawing(400,4400/17,-7,10,-4,7,

line(-10,0,15,0), line(0,-10,0,10), green(line(-2,5,70/233,294/233)),
locate(-2,5.6,A),locate(-5,-2,B), locate(8,6,C),
triangle(-5,-2,-2,5,8,6), locate(70/233,294/233,D) 

 )}}}

The green line segment AD is the altitude.

Let's reverse the choices to consider:</pre>d) the length of AB and the slope of AC<pre>No, the length of AB nor the slope of AC will help you find AD</pre>c) the midpoint of BC and the coordinates of A<pre>No, because D is not necessarily the midpoint of BC.  It would
only be if triangle ABC were isosceles, and that is not necessary.</pre>b) The negative reciprocal of the slope AB.<pre>No because we do not need a perpendicular to AB to find AD's equation.</pre>a) The coordinates of A and the negative reciprocal of the slope BC.<pre>Yes because AD is perpendicular to BC, and will have the slope
which is the negative reciprocal of the slope of BC, and if we
know the coordinates of A, we will have a point on AD and the
slope of AD, and we can find the equation of AD using the point-
slope formula.

Answer (a).

Edwin</pre>