# Math Trig. Help!

• Sep 9th 2008, 11:11 AM
<3<3
Math Trig. Help!
An aircraft flies from its base 200km on a bearing 162 degrees, then 350 km on a bearing 260 degrees, and then returns directly to base. Calculate the length and bearing of the return journey!!!

• Sep 9th 2008, 11:41 AM
Simplicity
Quote:

Originally Posted by <3<3
An aircraft flies from its base 200km on a bearing 162 degrees, then 350 km on a bearing 260 degrees, and then returns directly to base. Calculate the length and bearing of the return journey!!!

Draw a diagram, it does half the question for you.

To work out the length it travels, use the cosine rule. $a^2 = b^2 + c^2 - 2bc\cos A$, where:
• $a,b,c$ are your lengths.
• $A$ is the angle opposite to the side $a$.
• Sep 9th 2008, 11:50 AM
shinhidora
As I replied to your other topic!

If you draw that out, you should en up with a triangle...

'A' being your base
'B' being your first point where you change bearing
'C' being the point where you return to your base

â = 180 - 162 = 18 degrees
b = 360 - 260 = 100 degrees
c = 180 - 18 - 100 = 62 degrees

AB = 200km
BC = 350 km
CA = X

you need to find x :p I drew it out in paint but it ended up horribly so nvm :p

You know how to do it now? Or are the formulae what you're looking for?