Denote the origin by O , (2, 1) by P and (-1, 2) by Q. If R and S are marked on the XY -plane such that OR = 30Â units, OS = 40 units. P lies on OR and Q on OS , then what is the distance between R and S , in the given unit?
Join the points O and P, the slope of this line is 1/2/ Join the points O and Q, the slope of this line is -2. The product of slopes of two perpendicular lines will be -1. These two lines are perpendicular. The point R lies on OP and S on OQ. Since these two lines are perpendicular, the line joining R and S will be the hypotenuse. So it is $$\sqrt{\ 30^2+40^2}=50$$.