Note that 7pi/6 is equivalent to 6pi/6 + 1pi/6, which is equivalent to pi plus pi/6, or 180 degrees plus 30 degrees. 7pi/6 is in Quadrant III; its "opposite side" is -1 and its "hypotenuse is 2." Thus, the sine of (7pi/6) is the ratio
opp side -1
------------------- = ------------ This matches Answer B.
