Hello, symmetry!
Two cars are approaching an intersection.
One is 2 miles south of the intersection and is moving at 30 mph.
The other car is 3 miles east of the intersection and is moving at 40 mph.
Express the distance between the cars as a function of time . Code:
C 3  40t B 40t Q
*         *     *
 *
 *
2  30t  * d
 *
 *
A*

30t 

P*
The first car starts at and drive north to the intersection .
In hours, it has gone miles to point .
. . Hence,
The other car starts at and drives west to .
In hours, it has gone miles to point .
. . Hence,
Using Pythagorus, the distance between them is: .
Simplifying, we get: .
Therefore: .