a)
N (-1, 5) = (x1,y1)
M (5,7) = (x2,y2)
slope formula:
m = slope = (y2-y1) / (x2-x1) = (7 -5 ) / (5 - (-1)) = 2/6
b) slope = 2/6
2/6 = x-7/y-5
side 1 = x-7
side 2 = y-5
c) because of the slope formula:
Points from the triangle:
M= (x1,y1) = (5,7)
N = (x,y) = (x,y)
Since the line is the same, the slope is the same always -