Answer: Russell is correct
The lines aren't perpendicular.
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Explanation:
Pick any two points from the red line to find the slope.
I'll pick (0,1) and (1,5).
m = slope
m = (y2-y1)/(x2-x1)
m = (5-1)/(1-0)
m = 4/1
m = 4
The red line has a slope of 4.
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Repeat the same steps for the blue line.
I'll pick the points (0,0) and (3,-1).
Ideally you should pick points that have whole numbers for x and y.
m = (y2-y1)/(x2-x1)
m = (-1-0)/(3-0)
m = -1/3
The blue line has slope of -1/3
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The red and blue lines have slopes of 4 and -1/3 respectively.
These numbers are not negative reciprocals of each other, so the lines are not perpendicular.
Put another way: the two slopes do not multiply to -1, which is why they aren't perpendicular.
Perpendicular slopes always multiply to -1 assuming neither line is vertical nor horizontal.
Therefore Russell is correct in stating the lines aren't perpendicular.
