Three guns are aimed at the center of a circle, and each fires a bullet simultaneously. The directions in which they fire are 1208 apart. Two of the bullets have the same mass of 4.50 × 1023 kg and the same speed of 324 m/s. The other bullet has an unknown mass and a speed of 575 m/s. The bullets collide at the center and mash into a stationary lump. What is the unknown mass?