a question about differentiation
P is a point 22m due east of a fixed point O and Q is a point 14m due south of O. A particle A starts at P and moves towards O at a speed of 4m/s while a particle B starts at Q at the same time as A and moves towards O at a speed of 3m/s. Find an expression for the distance between A and B t seconds after the start. Hence, find the value of t when the distance between A and B is a minimum and find this minimum distance.
i can't figure out how to relate them and make an expression.
i think i can do the latter part once the expression is found.