Find the exact value of the trigonometric function at the gi

Find the exact value of the trigonometric function at the given real number sin 7 pi/6 cos 17 pi/6 tan 7 pi/6

Solution

sin(7pi/6) = sin(7(30))

               =sin(210)

            = sin(180+30)

             =-sin30 = -1/2

cos(17pi/6) = cos(510)

                    = cos(360+150)

                    = cos(150)

                     = cos(180-30)

                       =-cos30

                       = - sqrt(3)/2

tan(7pi/6) = tan210

                 = tan(180+30)

                 = -tan30

                  = - 1/sqrt(3)