Solve the Problem $\theta$ Is the Vertex Angle of the Cone And

Solve the problem.

-An airplane flying faster than the speed of sound creates sound waves that form a cone. If $\theta$ is the vertex angle of the cone and $\mathrm { m }$ is the Mach number for the speed of the plane, then $\sin \frac { \theta } { 2 } = \frac { 1 } { \mathrm {~m} }$ $( \mathrm { m } > 1 )$ . Find the Mach number to the nearest tenth if $\theta = 60 ^ { \circ }$ .

A) 2
B) $2.6$
C) $3.1$
D) $1.8$