The Angle $\theta$ That the Wave Front of a Mach Cone Makes with Cone

The angle $\theta$ that the wave front of a Mach cone makes with the direction of travel of a supersonic aircraft is related to the speed of sound v and the speed of the supersonic aircraft (emitter) V_E by the formula

A) V_E = v cos $\theta$
B) v = V_E cos $\theta$
C) V_E = v sin $\theta$
D) v = V_E sin $\theta$