Final answer:
The mass of a triangle cannot be determined from the given information about the masses of a circle and a square without additional context or a defined relationship between their masses.
Step-by-step explanation:
The question about the mass of a triangle does not provide enough information to determine its mass based on the given masses of a circle and a square. In mathematics and physics, the mass of an object cannot be inferred just by knowing the masses of objects with different shapes unless a specific relationship is defined between their masses. Therefore, without additional context or a defined relationship, this question cannot be answered directly. Masses of objects in different shapes are not inherently related unless there's a direct physical or mathematical relationship established, such as uniform density or a specific composite object.