# What is the distance between the following polar coordinates?:  (2,(3pi)/8), (7,(3pi)/8)

But it's not necessary here. You can draw a line 2 units long, along the $\frac{3 \pi}{8}$ angle. Keep drawing another 5 units along that same angle, to mark a point 7 units out. Boom, you've got your answer: 5 units.