Two vehicles, a car and a truck, leave an intersection at the same time. The car heads east at an average speed of 30 miles per hour, while the truck heads south at an average speed of 70 miles per hour. Find an expression for their distance apart d (in miles) at the end of thours.
At the end of t hours, the two vehicles are miles apart.
(Simplify your answer. Type an exact answer, using radicals as needed.)