# Thread: Find trig identities of an angle

1. ## Find trig identities of an angle

find sin, cosine, and the tangent of the angle 11pi/12

2. Originally Posted by jumpman23
find sin, cosine, and the tangent of the angle 11pi/12
$\displaystyle \frac{11\pi}{12}$ is half of $\displaystyle \frac{11\pi}{6}$ ... use your half-angle identities.

3. Or, as an alternative, note that $\displaystyle \frac{11\pi}{12}=\frac{3\pi}4+\frac\pi6.$

4. sin(11pi/12) = sin(pi - 11pi/12) = sin(pi/12)
= sin( pi/3 - pi/4)
= 1/sqrt(2)[ sqrt(3) - 1 ] = [ sqrt(6) - sqrt(2) ]/ 2