Answer: The argument is valid by the law of syllogism.
Step-by-step explanation:
Law of syllogism in geometric arguments is similar to transitive property which tells that that if x=y and y=z then x=z.
Given premises: If the sides of a triangle are the same length, then the triangle is an equilateral triangle.
If a triangle is an equilateral triangle, then the measure of each angle is 60°.
Therefore by law of syllogism we can conclude that "If the sides of a triangle are the same length, then the measure of each angle is 60°."
