Mary is wrong because ∠A = ∠B = 63°, while ∠C = x ≠ 63°
A triangle is a polygon with three sides and three angles. Types of triangles are equilateral, isosceles and right angled.
An isosceles triangle is a triangle in which two sides and two angles are equal.
From the diagram:
∠A = ∠B (base angles)
Mary is wrong because ∠A = ∠B = 63°, while ∠C = x ≠ 63°
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