SOLUTION: To find an approximate length of a lake, a person walks 530 feet from one side of the lake to point B. He then turns 60o and walks 430 ft to the other side of the lake directly a

Algebra ->  Finance -> SOLUTION: To find an approximate length of a lake, a person walks 530 feet from one side of the lake to point B. He then turns 60o and walks 430 ft to the other side of the lake directly a      Log On


   

Question 1121025: To find an approximate length of a lake, a person walks 530 feet from one side of the lake to point B. He then turns 60o and walks 430 ft to the other side of the lake directly across from where he started. Find the length of the lake.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
To find an approximate length of a lake, a person walks 530 feet from one side of the lake to point B.
He then turns 60o and walks 430 ft to the other side of the lake directly across from where he started.
Find the length of the lake.
:
We can use the law of cosines a^2 = b^2 + c^2 - 2(bc)Cos(A)
where
A = 60 degrees
a = the length of the lake
b = 530
c = 430
:
a^2 = 530^2 + 430^2 - 2(530*430)*cos(60)
a^2 = 280900 + 184900 - 2(227900)*.5
a^2 = 465800- 227900
a = sqrt%28237900%29
a = 487.75 ft
:
:
that's the method, I'll let you check my math