trig

posted by .

give and exact value for cos(2pi/3)

  • trig -

    2 pi/3 radians = 360/3 = 120 degrees
    180 -120 = 60
    so
    60 degrees above -y axis in quadrant 2
    so
    -1/2

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. trig

    give exact value of cos 75 degrees. give exact value sin 15 degrees. give exact value sin 225 degrees. You will have to use the addition relations here. Notice 75 is 30 +45, 15 is 45-30, and 225 is 180 + 45. I will be happy to critique …
  2. Trig

    If cosx = 10/19 an pi < x < 2pi, find the exact value of cos x/2 Use the double angle formula. Cos 2Y= sin^2 Y - cos^2Y = 1-2Cos^2 Y. let y= x/2, and 2Y=x
  3. Trigonometry

    4. Find the exact value for sin(x+y) if sinx=-4/5 and cos y = 15/17. Angles x and y are in the fourth quadrant. 5. Find the exact value for cos 165degrees using the half-angle identity. 1. Solve: 2 cos^2x - 3 cosx + 1 = 0 for 0 less …
  4. trig

    determine the exact value for sin[cos^-1(4/5)] if XE [0,2pi]
  5. Trigonometry

    a. Find the exact value of sin (theta - pi/6) b. Find the exact value of cos (theta - pi/4) c. For what numbers x, -2pi less than or equal to x less than or equal to 2pi does cos x = -1 d. What is the range of the cosine function?
  6. trig

    Find the exact solutions of the equation in the interval [0,2pi). sin(x/2)+cos(x)=0
  7. Math- Trig

    1. Determine the exact value of cos^-1 (pi/2). Give number and explanaton. 2. Determine the exact value of tan^-1(sq. root 3). with explanation. 3. Determine exact value of cos(cos^-1(19 pi)). with explanation. 4. Determine the exact …
  8. Precalc with Trig

    What value(s) of x from 0 to 2pi solve the following equation: cos squared x - cos x - 6 = 0
  9. Trig hep, please? Thank you!

    1. Find the exact value of sin(195(degrees)) 2. If cot2(delta)=5/12 with 0(<or =)2(delta)pi, find cos(delta), sin(delta) , tan(delta). 3.find the exact value of sin2(x) if cos(x)= 4/5. (X is in quadrant 1) 4. Find the exact value …
  10. Math Trig Please Help!!!

    Find exact values for all the solutions to the equation cos theta = sqrt 3/2 for -2pi <= theta <= 2pi Theta = Theta = Theta = Theta =

More Similar Questions