For the floor plans given in exercise27, determine whether the side through the points (2, 3) and (11, 6) is perpendicular to the side through the points (2, 3) and (-3, 18).

Question

Compute the slopes of the two lines. If the product of the slopes is -1, then te lines are perpendicular.

In your case, the first line has a slope of m = (6-3)/(11-2)= 1/3 and the second line has a slope of
m = (18-3)/(-3 -2) = 15/(-5) = ?

You finish it.

You could also do the problem graphically by plotting the points, drawing the lines and using a protractor.