SOLUTION: Two planes leave an airport at the same time, one flying at 300 km/h and the other at 420 km/h. The angle between their flight paths is 75 degrees. After 3 hours, how far apart are

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Question 753571: Two planes leave an airport at the same time, one flying at 300 km/h and the other at 420 km/h. The angle between their flight paths is 75 degrees. After 3 hours, how far apart are they (to the nearest km)?
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Use Cosine Rule.
Imagine a triangle with angle 75 degrees
as vertex A
Aircraft flying at 300 km/hr - side AB
Aircraft flying at 420 km/hr - side AC
After 3 hours side AB measures 900km
After 3 hours side AC measures 1260km
We must calculate side a
a^2 = b^2 + c^2 - 2bcCosA
a^2 = 1260^2 + 900^2 - 2*1260*900*Cos 75
a^2 = 1810598.4
a = 1346km (Distance apart)
Hope this helps
:-)