Trigonometry

posted by .

use the appropriate trig identity (sum and difference, half angle, double angle) to find the exact value. 1)cos 255 degrees
2) sin 165 degrees
3) tan 285 degrees

  • Trigonometry -

    isn't 255 = 180+75=270-15 which is 270-30/2?


    isn't 165=180-30/2

    isn't 285=270+30/2?

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. MATH

    1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL STEPS) sin 2x - sin x = 0 2.) GIVEN: sin u = 3/5, 0 < u < ï/2 Find the exact values of: sin 2u, cos 2u and tan 2u using the double-angle formulas. 3.)Use …
  2. Algebra 2 Honors

    Find the exact value by using an appropriate sum or difference identity. cos(165) degrees
  3. Trigonometry

    Please review and tell me if i did something wrong. Find the following functions correct to five decimal places: a. sin 22degrees 43' b. cos 44degrees 56' c. sin 49degrees 17' d. tan 11degrees 37' e. sin 79degrees 23'30' f. cot 19degrees …
  4. Algebra II

    Multiple Choice (theta) means the symbol 0 with the dash in it. 1.)Which expression is equivalent to tan(theta)-(sec(theta))/(sin(theta))?
  5. TRIG/ALGEBRA

    1) Find the exact value. Use a sum or difference identity. tan (-15 degrees) 2) Rewrite the following expression as a trigonometric function of a single angle measure. cos 3x cos 4x - sin 3x sine 4x
  6. Math-Trigonometry

    Use the half-angle formulas to find the exact values. Cosine 165 degrees, Sine 157 degrees 30' and tan pi/8
  7. trigonometry

    We begin by setting t=sin 18 degrees we weill think of t an an "unknown" angle and solve to get the exact value. Use a double angle formula to show that cos 36 degrees=1-2t^2
  8. trig

    use a half-angle identity to find the exact value of tan 105 degrees.
  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. Trigonometry - Identities

    If tan 2x = - 24/7, where 90 degrees < x < 180 degrees, then find the value of sin x+ cos x. I applied various identities and tried manipulating the problem to get sin x + cos x = sin(arctan(-24/7)/2) + cos(arctan(-24/7)/2) I …

More Similar Questions