### Home > CALC > Chapter 7 > Lesson 7.1.4 > Problem 7-43

7-43.

Let the eastbound car be at a distance *x* from the intersection and the northbound car at distance *y*.

Write an equation for the distance between them.

Implicitly differentiate the distance equation with respect to time. This will create a rate equation.

Evaluate.

≈ 48.788 mph