11-12 Two trains; one going to east, and the other is heading north

Problem 11
A train starting at noon, travels north at 40 miles per hour. Another train starting from the same point at 2 PM travels east at 50 miles per hour. Find, to the nearest mile per hour, how fast the two trains are separating at 3 PM.
 

Problem 12
In Problem 11, how fast the trains are separating after along time?
 

Trigonometry

Video

The Six Trigonometric Functions

  1. $\sin \theta = \dfrac{a}{c}$
  2. $\cos \theta = \dfrac{b}{c}$
  3. $\tan \theta = \dfrac{a}{b}$
  4. $\csc \theta = \dfrac{c}{a}$
  5. $\sec \theta = \dfrac{c}{b}$
  6. $\cot \theta = \dfrac{b}{a}$