Answer:
Slope is 2/3
Step-by-step explanation:
What you can do is use the first two coordinates. This would get the formula to look like this:

From here you get ⅔ for the slope.
They can NOT. A right angle is 90°. An obtuse angle is greater than 90°. All the angles in a triangle must add up to exactly 180°. If two angles are greater than 90° then they will add up to greater than 180, beacuse 90 plus 90 equals 180. You cannot have a triangle with two obtuse angles because they will add up to greater than 180°.
Make them both equal to y
y=-2x+6
2y=x+6 y=1/2x+3
These are perpendicular since ones slope is -2 and the other is the opposite, 1/2.