Question

We are given that ΔABC is isosceles with AB ≅ AC. Using the definition of congruent line segments, we know that . Let’s assume that angles B and C are not congruent. Then one angle measure must be greater than the other. If m∠B is greater than m∠C, then AC is greater than AB by the . However, this contradicts the given information that . Therefore, , which is what we wished to prove. Similarly, if m∠B is less than m∠C, we would reach the contradiction that AB > AC. Therefore, the angles must be congruent.

Answer 1

$AB= AC = 1.3 cm, DE = DF = 1.9 cm, and GH = GJ = 2.3 cm$

the triangles are isosceles.

Answer 2

First box: AB = AC
Second box: triangle parts relationship theorem
Third box: side AB is congruent to side AC
Fourth box: angle B is congruent to angle C