1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Solving the triangle

  1. Apr 20, 2008 #1
    1. The problem statement, all variables and given/known data
    use the information to solve the triangle: b=1, c=the square root of (3)+1, B=15 degrees.
    given that sin15 degrees =the square root of 6 -the square root of 2 divided by 4. FYI.. is in the square root and than add one.

    2. Relevant equations
    The formulas given the law of sin sinA/a=sinB/b=sinC/c
    The law cosine

    3. The attempt at a solution
    I used the law of sin to find angle C. The problem is written out as the square root of (3)+1 Sin(15)/1. I came out with .70 degrees for angle c. For some reason I can't get that answer again. Also I'm not sure which formula I should be using.
  2. jcsd
  3. Apr 21, 2008 #2

    Gib Z

    User Avatar
    Homework Helper

    Well using the sine rule, we get [tex] \frac{\sin 15*}{1} = \frac{\sin C}{\sqrt{3}+1}[/tex].

    The * I used to denote degrees. Anyway, to get the angle C, we must get Sin C by itself on one side. Once you do that, simplify the Sin 15 degrees from what it gave you in the question, and also take out a factor of sqrt2 from it. Then it should simplify very nicely, you shouldn't even need a calculator for it. You get some nice common angle, not 0.70 degrees.
  4. Apr 21, 2008 #3


    User Avatar
    Science Advisor

    msdenise15, you forgot to take the arcsine! What you calculated was that sin(C)= .707..= sqrt(2)/2. And, as Gibz said, that's a "well known" angle.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook