.5x12 (30+42)
v v
6 * 72= 432 ft
Slope of perpendicular is -1/3.
Then equation is
y-5=(-1/3)(x+9)
Let's use the "elimination by addition/subtraction" method to solve this system for x and y.
<span> -8x=72-16y
4x=-92+16y <= Mult. all 3 terms by 2: 8x = - 184 + 32y
Now combine the following, column by column:
</span><span> -8x= 72-16y
</span>8x = - 184 + 32y
-----------------------
0 = -112 + 16y. Solving for y, 16y = 112, and y = 7.
Now subst. 7 for y in either of the original equations and calculate x:
<span>4x=-92+16(7) => 4x = -92 + 112 = 20. Then x = 5.
Solution is 5, -7 (or, better written) (5, - 7).</span>
The answer is B.
I hope this helps. :)
