No. If you don't specify how long the arms of the short sides of the right triangle need to be, then you can make m3 be whatever you want, and you'll still have a right-triangle with 1/x and -x as the gradient of two of the sides.
True I think I might of head down the wrong path I am trying to solve the following problem in the diagram below. I am unsure how u1 is obtained. I assume that the gradient of the green line is used to solve as shown below