You can put this solution on YOUR website! Use the cosine angle addition formula. cos(165°) = cos(120° + 45°)

Feb 16, 2017 · How do you use the sum or difference identities to find the exact value of #cos165^circ#?

Feb 25, 2017 · tan (-165) = (sqrt(2 - sqrt3))/(sqrt(2 + sqrt3) sin (-165) = sin (195) --> co-terminal. Call sin (195) = sin t Use trig table and unit circle: cos 2t = cos 390 = cos (30 + 360) = cos 30 = sqrt3/2 Use trig identity: 2sin^2 t = 1 - cos 2t 2sin^2 t = 1 - sqrt3/2 = (2 - sqrt3)/2 sin^2 t = (2 - sqrt3)/4 sin t = +- (2 - sqrt3)/2 Since sin (- 165) is negative, then, take the negative answer. sin ...

cos 165 = - sqrt(2 + sqrt3)/2 Use half angle identity: cos (a/2) = +- sqrt((1 + cos a)/2) In this case, cos (a/2) = cos 165, and cos a = cos 330. Trig table gives ...

Question 1159668: Use half-angle formulas to find the exact values. cos 165° I got /2 which is wrong. This is my work:

May 4, 2015 · 180^o = pi " radians" 165^o = 165^o * (pi " radians")/(180^o) = 2.88 " radians" (approx.)

You can put this solution on YOUR website! find the exact value of the expression sin 165 degrees. ** sin (x+y)=sinxcosy+cosxsiny

Sep 21, 2015 · Find sin (-165) Ans: - (sqrt6 - sqrt2)/4 sin (-165) = - sin (165) = - sin (45 + 120) Trig Table --> sin (45 + 120) = sin 45.cos 120 + sin 120.cos 45 = (sqrt2/2)(-1/2 ...

Question 258565: Find the exact value of the expression sin 165 degrees Answer by stanbon(75887) ( Show Source ): You can put this solution on YOUR website!

Question 42619: Find the exact value of sin 165°. Thank You Answer by ... sin 120 cos 45 + cos 120 sin 45