Question

if the value to the nearest thousandth, of cosO is -0.385, which of the following could be true about O? A. 0<O<pi/6 B. pi/6<O<pi/3 C. pi/3<O<pi/2 D. pi/2<O<2pi/3 E. 2pi/3<O<pi

Answer 1

Its the last choice there. Converting that to degrees you get the interval of 90<O<120, which is the only angle that lies in the quadrant in which cosine is negative, which is the second quadrant. Cosine is also negative in the third quadrant, but you don't have choices for the third quadrant.