Final answer:
The question involves solving for variables in equations related to the conservation of momentum and rotational dynamics in Physics. Due to the lack of context, the correct equation for ∠1 is unclear.
Step-by-step explanation:
The question seems to be related to the principles of conservation of momentum and rotational dynamics in Physics, specifically involving collisions and angular measurements. It refers to solving for the unknowns in two equations derived from conservation laws, where m is the mass and v denotes velocity. The correct equation regarding the measure of ∠1 is not fully clear from the context provided, as it seems to be a collision problem involving angles. Normally, you would have initial and final velocities related to each other through the masses and angles described as the components of the vectors involved in a collision. If this were a linear collision scenario in Physics, the measure of the angle after the collision would not be linearly related to the masses and velocities like those given in the options provided.