math

Use an Addition or Subtraction Formula to find the exact value of the expression.

Sin(−5π/12)

  1. 👍 0
  2. 👎 0
  3. 👁 121
  1. some students have less difficulty if the angle is in degrees.
    Let's try this approach ....
    5π/12 radians = 75°

    so sin(-5π/12)
    = sin(-75°) which is in quadrant IV, making the sine negative
    = -sin(75°)
    = -sin(30° + 45°)
    = -(sin30cos45 + cos30sin45)
    = -( (1/2)(√2/2) + (√3/3)(√2/2) )
    = - √2/4 - √6/4

    so sin(05π/12) = -√2/4 - √6/4

    check:
    on my calculator:
    sin(-5π/12) = -.9659...
    and -√2/4 - √6/4 = -.9659..
    My answer is correct

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    1. Let (-7, 4) be a point on the terminal side of (theta). Find the exact values of sin(theta), csc(theta), and cot(theta). 2. Let (theta) be an angle in quadrant IV such that sin(theta)=-2/5. Find the exact values of sec(theta)

    asked by Kandee Johnson on May 15, 2011
  2. Pre-Calc

    1) Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number. cos 12° cos 18° − sin 12° sin 18° And Find its exact value. 2) Use an Addition or Subtraction Formula to write the

    asked by Alyssa on April 13, 2015
  3. Pre-Calc

    I am really struggling with how to do these problems, I posted them a few minutes ago but the answers/work shown was incorrect. 1) a) Use an Addition or Subtraction Formula to write the expression as a trigonometric function of

    asked by Alyssa on April 13, 2015
  4. Trigonometry help

    If sin(x) = 1/3 and sec(y) = 13/12 , where x and y lie between 0 and π/2, evaluate the expression using trigonometric identities. (Enter an exact answer.) sin(x + y)

    asked by carter on August 30, 2011
  5. Calculus

    find the exact value of sin 11pi/12 using the sum or difference formula.

    asked by Josh on July 19, 2011
  1. Precalculus check answers help!

    1.) Find an expression equivalent to sec theta sin theta cot theta csc theta. tan theta csc theta sec theta ~ sin theta 2.) Find an expression equivalent to cos theta/sin theta . tan theta cot theta ~ sec theta csc theta 3.)

    asked by Kelsey on May 30, 2012
  2. Alg2/Trig

    Find the exact value of the trigonometric function given that sin u = 5/13 and cos v = -3/5. (Both u and v are in Quadrant II.) Find csc(u-v). First of all, I drew the triangles of u and v. Also, I know the formula of sin(u-v) is

    asked by Vincent on June 4, 2009
  3. Pre-Cal

    Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number. (tan(74°)-tan(14°))/(1+tan(74°)tan(14°)) =__________ Find it's exact value (not decimal form) =__________ Note: A

    asked by Amber on July 7, 2016
  4. Math

    How is combing radicals by addition and subtraction similar to combining monomial expressions by addition and subtraction? Please use examples.

    asked by Eva on February 8, 2017
  5. calculus

    Use the even odd properties to find the exact value of the expression. It may be helpful to draw the unit circle graph sin(-pi)

    asked by kelly on November 18, 2007
  6. trig

    find the exact value of the expression , sin-1(-0.5)

    asked by cindi on August 13, 2012

You can view more similar questions or ask a new question.