 A ladder 10m long rests against a vertical wall. If the bottom of the ladder slides away from the wall at a rate of 1m/s how fast is the top of the ladder sliding down the wall when the ladder is 4m from the wall.

 Step 1: ◦ Draw Diagram  Step 2 ◦ Introduce Notation  Step 3 ◦ Express info. In terms of variables  Step 4 ◦ Relate the quantities  Step 5 ◦ Differentiate (Chain rule)  Step 5 ◦ Evaluate required rate

 A street light is mounted at the top of a 15 ft. pole.  A man 6 ft. tall walks away from the pole at a speed of 5 ft/s along a straight path.  How fast is the tip of his shadow moving when he is 40 ft. from the pole?  Step 1: ◦ Draw Diagram  Step 2 ◦ Introduce Notation  Step 3 ◦ Express info. In terms of variables  Step 4 ◦ Relate the quantities  Step 5 ◦ Differentiate (Chain rule)  Step 5 ◦ Evaluate required rate