math

Write the given expression as the cosine of an angle. cos 60° cos 65° − sin 60° sin 65°

  1. 👍 0
  2. 👎 0
  3. 👁 217
asked by terry
  1. you should recognize this as the use of
    cos(A+B)

    cos 60° cos 65° − sin 60° sin 65°

    = cos(60°+65°)
    = cos 125°

    1. 👍 0
    2. 👎 0
    posted by Reiny

Respond to this Question

First Name

Your Response

Similar Questions

  1. trig

    Reduce the following to the sine or cosine of one angle: (i) sin145*cos75 - cos145*sin75 (ii) cos35*cos15 - sin35*sin15 Use the formulae: sin(a+b)= sin(a) cos(b) + cos(a)sin(b) and cos(a+b)= cos(a)cos(b) - sin(a)sin)(b) (1)The

    asked by Paul C on November 26, 2006
  2. Math

    Write the expression as the sine, cosine, or tangent of an angle. cos 0.96 cos 0.42 + sin 0.96 sin 0.42 Is this cos 0.54?

    asked by Anonymous on October 25, 2015
  3. TRIG!

    Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6 x=1 - (3/4)sin^2 2x work on one side only! Responses Trig please help! - Reiny, Monday, February 23, 2009 at 4:27pm LS looks like the sum of cubes sin^6 x +

    asked by hayden on February 23, 2009
  4. math

    Write the expression as the sine, cosine, or tangent of an angle. sin(2π/9)cos(3π/8)+cos(2π/9)sin(3π/8)

    asked by Stella on June 10, 2018
  5. Pre-Calculus

    Write the following expression as the sine, cosine or tangent of an angle. cos 3x cos 2y + sin 3x sin 2y

    asked by Mariam on January 24, 2018
  6. maths

    Choose the two options which are true for all values of x 1) cos (x) = cos ( x – pie/2) 2) sin (x + pie/2) = cos (x – pie/2) 3) cos (x) = sin (x – pie/2) 4) sin (x) = sin (x + 4pie) 5) sin (x) = cos (x – pie/2) 6) sin^2

    asked by katie on April 22, 2007
  7. algebra

    Can someone please help me do this problem? That would be great! Simplify the expression: sin theta + cos theta * cot theta I'll use A for theta. Cot A = sin A / cos A Therefore: sin A + (cos A * sin A / cos A) = sin A + sin A = 2

    asked by Valerie on February 18, 2007
  8. pre-cal

    Simplify the given expression........? (2sin2x)(cos6x) sin 2x and cos 6x can be expressed as a series of terms that involve sin x or cos x only, but the end result is not a simplification. sin 2x = 2 sinx cosx cos 6x = 32 cos^6 x

    asked by ethan on May 17, 2007
  9. precalculus

    write each expression as the sine, cosine or tangent of a double angle. then find the exact value of the expression. a. 2sin 22.5 cos 22.5 b. cos^2 105- sin^2 105

    asked by ama on July 6, 2012
  10. 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 the

    asked by MAKITA on April 10, 2009

More Similar Questions