# Trigonometry to solve complex shapes

• May 13th 2007, 03:05 PM
turbod15b
Trigonometry to solve complex shapes
how do i use the COSINE RULE to calculate the length across BF

http://i10.photobucket.com/albums/a1...g/DSC01024.jpg

:confused:
• May 13th 2007, 07:48 PM
topsquark
Quote:

Originally Posted by turbod15b
how do i use the COSINE RULE to calculate the length across BF

http://i10.photobucket.com/albums/a1...g/DSC01024.jpg

:confused:

Simple:
BF^2 = AB^2 + AF^2 - 2*AB*AF*cos(50)

-Dan
• May 14th 2007, 10:06 AM
turbod15b
thanks buy can u make it a little bit more simpler plz lol
sorry:(
• May 14th 2007, 03:28 PM
topsquark
Quote:

Originally Posted by topsquark
Simple:
BF^2 = AB^2 + AF^2 - 2*AB*AF*cos(50)

-Dan

Quote:

Originally Posted by turbod15b
thanks buy can u make it a little bit more simpler plz lol
sorry:(

:confused: What more simple do you need?

From the diagram
AB = 5
AF = 2.5

It's a "plug-n-chug" problem. Just put the numbers in:
BF^2 = 5^2 + 2.5^2 - 2*5*2.5*cos(50)

BF^2 = 15.1803

BF = 3.8962 m

-Dan