Use a Graphing Device to Find the Maximum and Minimum $y = \cos x - \frac { 1 } { 2 } \cos 2 x$

Use a graphing device to find the maximum and minimum values of the function $y = \cos x - \frac { 1 } { 2 } \cos 2 x$

A) maximum value: $\frac { 4 } { 3 }$
, minimum value: $0$

B) maximum value: $\frac { 3 } { 4 }$
, minimum value: $- 1$

C) maximum value: $\frac { 3 } { 4 }$
, minimum value: $- \frac { 3 } { 2 }$

D) maximum value: $\frac { 3 } { 4 }$
, minimum value: $- \frac { 4 } { 3 }$

E) none of these