Final answer:
Using geometrical properties and postulates including the Linear Pair Postulate and the Corresponding Angles Theorem, it's demonstrated that the angle m/⟩FAC equals 121° in Greg's fence construction scenario due to the parallel nature of the sides.
Step-by-step explanation:
The statements in the question address a geometric scenario where Greg is constructing a fence with parallel sides and needs to establish angle measures. To explain how Greg can show that m/⟩FAC equals 121°, we use a combination of the Linear Pair Postulate, the Corresponding Angles Theorem, and properties to describe the relationships between angles formed when parallel lines are intersected by a transversal. Here are the steps involved in proving that m/⟩FAC equals 121°:
- Given: ED || FB, m/⟩ZECG = 121°.
- Linear Pair Postulate: m/⟩ZECG + m/⟩ECA = 180° (because they are a linear pair).
- Subtraction Property: m/⟩ZECG = m/⟩FAC as they are corresponding angles and lines ED and FB are parallel.
- Transitive Property: If m/⟩ZECG = 121° and m/⟩ZECG = m/⟩FAC, then m/⟩FAC = 121°.
Summarily, given the parallel nature of lines ED and FB as well as the corresponding angles created, through the use of geometrical properties and postulates, we determine that m/⟩FAC is indeed 121°.