Question

Akiko leaves the mall and drives directly west at a speed of 60 mph. At the same time, Kosuke leaves the mall and drives 40 degrees north of east at a speed of 45 mph. How far apart are they after 45 minutes? Round the answer to the nearest tenth of a mile.
A.17.4 milesB.28.9 milesC.44.5 milesD.74.1 miles

Answer 1

You know that Akiko is 45 miles from the origin...Kosuke is (135/4) miles from the origin... You can draw a figure to clearly see the situation.

you "know" that the angle between their routes is 140º 

the side opposite (140º) is the distance between them... 

c^2 = (45)^2 + (135/4)^2 - 2(45)(135/4) cos 140 

c ≈ 74.1 mile

Hope this answers the question.