To get locus of q: dy/dx = 1/t , then differentiate x and y values for q in terms of t, then use chain rule (dy/dx = dy/dt x dt/dx) and you get a value for t. Then sub in values for t into x and y, you get x= 3^1/2(a)/2 , y= a/2. Square both and add together and you get a^2