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Homework Help: Find the Angle (Geometry

  1. Jan 7, 2010 #1
    1. The problem statement, all variables and given/known data
    See the attachment

    3. The attempt at a solution
    Is the answer simply 70-40=30?

    Attached Files:

  2. jcsd
  3. Jan 7, 2010 #2


    Staff: Mentor

    You're trying to find angle 1, right? It looks to me like you are given that it is 40 degrees.
  4. Jan 7, 2010 #3
    I'm pretty sure 40 degrees refers to that arc of the circle. In this case, you need two formulas:

    1) Angle inside circle equals one-half of the sum of the intercepted arcs.
    2) Angle outside circle equals one-half of the difference of the intercepted arcs.
  5. Jan 8, 2010 #4
    70 = .5 (40+x)
    x = 100

    Angle 1 = .5(100+40)
    Angle 1 = 70

    However this answer is not an option. Where is my mistake?
    Last edited: Jan 8, 2010
  6. Jan 8, 2010 #5
    Your mistake is in this line. The angle outside the circle is equal to half the difference of the intercepted arcs.
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