Let the centre be O and the line with one end point at the centre and another at the chord CD touches the chord at S .
So CS is the half of 36.7 = 18.35
[tex] sin \angle COS = \frac{18.75}{21.8} [/tex]
[tex] \angle COS = sin^{-1}(\frac{18.75}{21.8}) =59.35 degree [/tex]
Therefore,
[tex] \angle COD =2*59.35 =118.7 [/tex]
Therefore the measurement of arc CD is 118.7 degree.
