# AP CALC

Two roads intersect at right angles. At a certain moment, one bicyclist is 8 miles due NORTH of the intersection traveling TOWARDS the intersection at a rate of 16 miles/hour. A second bicyclist is 10 miles due WEST of the intersection traveling AWAY from the intersection at 12 miles/hour.
(a) How fast is distance between the two bicyclists changing at this moment?

1. 👍
2. 👎
3. 👁
1. make a diagram, let the distance the north biker is from the intersection be y miles, let the distance the west biker is from the intersection be x miles
Let the distance between them be D
D^2 = x^2 + y^2
2D dD/dt = 2x dx/dt + 2y dy/dt

given:
dx/dt = 12 mph
dy/dt = -16 mph (y is decreasing)
find dD/dt when x=10 and y=8
then D^2 = 100+64
D = √164

dD/dt =(2(10)(12) + 2(8)(-16))/(2√164) = .....

you finish the arithmetic

1. 👍
2. 👎
2. My final answer was -8/square root of 164. Is that correct?

1. 👍
2. 👎
3. I believe the correct answer is 0.635 but i got 0.625.

1. 👍
2. 👎
4. poooop

1. 👍
2. 👎

## Similar Questions

1. ### Math

A surfer drives his dune buggy out into the sand dunes.He follows his compass 10 miles due north and then turns due west. If he ends up approximately 35 miles from where he started how far west did he travel? a- 10 miles b- 25

2. ### Math

1. Write the following reversible as a biconditional: If two perpendicular lines intersect, they form four 90* angles. A) Two intersecting lines are perpendicular if and only if they form four 90* angles. B) Two intersecting,

3. ### Geometry

Two straight pipes intersect under a circular garden and intercept non-adjacent arcs that measure 34 degrees and 108 degrees. What is the measure of the acute vertical angles formed where the two pipes intersect?

4. ### geometry

when two lines intersect, they form two pairs of "opposite" angles called _________ angles?

1. ### math

There is something wrong with this definition for a pair of vertical angles: “If AB and CD intersect at point P, then APC and BPD are a pair of vertical angles.” Sketch a counterexample to show why it is not correct. Can you

2. ### math

1. Two roads intersect at an angle of 52.7 degrees, with a field in between. A girl is walking on one of the roads 1.5miles from their intersection. Her house lies 0.85 miles from the intersection along the other road. If she cuts

3. ### math

two lines intersect in a plane and form four angles. one of the angles formed by this intersection is a 53degree angle. What are the measures of the other three angles? explain your answer

4. ### physics

a bicyclist is coasting on level ground at 32.35m/s. The bicyclist coasts up an incline of 20.5m at a 30degree angle. How fast is the bicyclist traveling when he grabs the limb?

1. ### geometry

which of the following statements are true? a. if two angles form a linear pair, then the angles are supplementary b. if two angles are right angles, then the angles are complementary c. if two angles have the same measure, then

2. ### Roman history

Which fact most clearly shows the difficulty in defending the Roman empire against invasion? A. At its height, the empire likely had a population as high as 100 million. B. At its height, the empire comprised nearly 1.7 million

3. ### geometry

Two lines intersect, forming two pairs of vertical angles. One of these angles is 110°. What are the measures of the three remaining angles? a 70, 70, 180 b 70, 70, 70 c 110, 70, 70 d 110, 110, 70 is it d?

4. ### geometry

In rhombus MPKN with an obtuse angle K the diagonals intersect each other at point E. The measure of one of the angles of a ∆PKE is equal 16°. Find the measures of all angles of ∆PKE and ΔPMN.