Here\'s the problem statement: Two people start from the same point. One walks e
ID: 2828607 • Letter: H
Question
Here's the problem statement:
Two people start from the same point. One walks east at 6 mi/h and the other walks northeast at 3 mi/h. How fast is the distance between the people changing after 15 minutes? (Round your answer to three decimal places.)
3.441 mi/h
I can't seem to get the answer at all.
I know the process goes:
1) law of cosines z^2 = x^2 + y^2 - xycos(theta) <- solve for z
2) take derivative of this, solve for dz/ dt (subbing in 6/4 for x, 6 for dx/dt, 3/4 for y, and 3 for dy/dt)
If anyone can figure out where I'm going wrong and what the exact answer is in mi/h, that would be perfect and I will rate perfect. Thank You!
Explanation / Answer
Law of cosines states that
z^2 = x^2 + y^2 - 2xycos(theta), you missed out a 2
Solve with 2 and you will get the result ... your approach is right