A police car is located 60 feet to the side of a straight road.

A red car is driving along the road in the direction of the police car and is 130 feet up the road from the location of the police car.

The police radar reads that the distance between the police car and the red car is decreasing at a rate of 100 feet per second.

How fast is the red car actually traveling along the road?

Calc. 1 I used Pythagorean Theorem to get the hyp. Then pluged in the givens into the derivative of Pyth. theorem.

I drew this as a triangle where x direction = 60, y direction = 120. dL/dt = -100. Got L=143.18 from Pyth. Theorem. L = hypotenuse. L^2=X^2+y^2. d/dy(L^2=X^2+y^2) is 2L*dL/dt=2x*dx/dt + 2y*dy/dt. I put 0 in for dx/dt bacause the police car isn't moving, then solved. AHH idk

I keep getting the wrong answer. How would you guys do this?

Question

A police car is located 60 feet to the side of a straight road.

A red car is driving along the road in the direction of the police car and is 130 feet up the road from the location of the police car.

The police radar reads that the distance between the police car and the red car is decreasing at a rate of 100 feet per second.

How fast is the red car actually traveling along the road?

Calc. 1 I used Pythagorean Theorem to get the hyp. Then pluged in the givens into the derivative of Pyth. theorem.

I drew this as a triangle where x direction = 60, y direction = 120. dL/dt = -100. Got L=143.18 from Pyth. Theorem. L = hypotenuse. L^2=X^2+y^2. d/dy(L^2=X^2+y^2) is 2L*dL/dt=2x*dx/dt + 2y*dy/dt. I put 0 in for dx/dt bacause the police car isn't moving, then solved. AHH idk

I keep getting the wrong answer. How would you guys do this?