Question #400f1

1 Answer
Mar 6, 2017

232

Explanation:

Use unit circle, trig table , and property of complement arcs.
sin(11π12)=sin(π12+π)=sin(π12)
Evaluate sin(π12) by using trig identity:
2sin2a=1cos2a.
In this case,
2sin2(π12)=1cos(π6)=132=232
sin2(π12)=234
sin(π12)=±232.
Sine sin(π12) is positive, take the positive value.
Finally, sin(11π12)=sin(π12)=232