Question

Two cars are traveling along perpendicular roads, car A at 40 mph and car B at 60 mph. At noon, when car A reaches the intersection, car B is 90 miles away, and moving toward it. Find the rate, in miles per hour, at which the distance between the cars is changing at 1pm.

-40

68

4

-4

40

Answer 1

Did you try to solve this question?

Answer 2

nope

Answer 3

hint: draw a diagram

Answer 4

This is a calculus question.

Answer 5

Calculate the distance between them using the distance formula.

Answer 6

d=tv?

Answer 7

d^2 = (40t)^2 + (90 - 60t)^2

differentiate w.r.t. time

Answer 8

d^2=2500?

Answer 9

d=sqrt 2500

Answer 10

d=50?

Answer 11

not an option.