Rút gọn các biểu thức sau: C = 2sin ($\frac{π}{2}$ + x) + sin (5π - x) + sin ( $\frac{3π}{2}$ + x) + cos ( $\frac{π}{2}$ + x) D = cos (5π - x) - sin ( $\frac{3π}{2}$ + x) + tan ($\frac{3π}{2}$ - x) + cot (3π - x)

`C=2sin(pi/2+x)+sin(5pi-x)+sin((3pi)/2+x)+cos(pi/2+x)`

`=2sin(pi/2+x)+sin(5pi-x)+sin(pi+(pi)/2+x)+cos(pi/2+x)`

`=2cosx-sin(-x)-sin(pi/2+x)-sinx`

`=2cosx+sinx-cosx-sinx`

`=cosx`

`D=cos(5pi-x)-sin((3pi)/2+x)+tan((3pi)/2-x)+cot(3pi-x)`

`=cos(5pi-x)-sin(pi+(pi)/2+x)+tan(pi+(pi)/2-x)+cot(3pi-x)`

`=-cos(-x)+sin(pi/2+x)+tan(pi/2-x)+cot(-x)`

`=-cosx+cosx+cotx-cotx`

`=0`