# How far was the pilot from starting point?

• Sep 23rd 2012, 02:48 PM
How far was the pilot from starting point?

(Crying)

A pilot flew for 210 miles at 21degree and then 147 miles at 162 degree. How far was he from starting point?
• Sep 23rd 2012, 03:12 PM
skeeter
Re: How far was the pilot from starting point?
start by making a sketch of the problem ... looks to me like a task involving the cosine law.
• Sep 23rd 2012, 03:35 PM
Re: How far was the pilot from starting point?
Thanks for the diagram sir..
∠ABC = 21 + (180 - 162) = 39° Is that correct sir?
• Sep 23rd 2012, 03:40 PM
skeeter
Re: How far was the pilot from starting point?
Quote:

Thanks for the diagram sir..
∠ABC = 21 + (180 - 162) = 39° Is that correct sir?

if you mean the acute angle at the top of the position triangle, yes.
• Sep 23rd 2012, 03:43 PM
Re: How far was the pilot from starting point?
Using the law of cosines:
This will be my new formula right?

b = √(210² + 147² - 2 * 210 * 147 * cos 39°)
• Sep 23rd 2012, 05:48 PM
bjhopper
Re: How far was the pilot from starting point?
formula is a^2+b^2 - c^2 / 2ab = cos 39 deg Solve for c given a and b
• Sep 25th 2012, 03:08 AM
skeeter
Re: How far was the pilot from starting point?
Quote: