Answer:

Step-by-step explanation:
We know that the parabola faces downard, and hence must have a negative first term, so that eliminates the first and third options.
The vertex of the parabola has an x-value of 2, so it must be of the form
.
Combining these, we have that the answer is 
There's no way to tell without seeing the picture of the triangle.
Try writing it in point-slope form and you will see why you have a problem.
slope m is equal to (y2-y1)/(x2-x1):
m = (y2-y1)/(x2-x1) = (2-6)/(-6 - -6) = -4/0
The denominator has a zero, so it is undefined.
Since the point-slope form requires "m" to be defined, you can't write the equation of the line using point-slope form.