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In two triangle ABC and DEF, if AB = BC ...

In two triangle ABC and DEF, if AB = BC , `angleB=angleE`, DE=EF and BC = Ef , then which of the following statements is CORRECT ?

A

Triangles are congruent only .

B

Triangles are isosceles only .

C

Both triangles are congruent and isosceles

D

Both the triangles are neither congruent nor isosceles .

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the given information about triangles ABC and DEF step by step. ### Step 1: Understand the Given Information We are given: - AB = BC (Two sides of triangle ABC are equal) - ∠B = ∠E (Angle B in triangle ABC is equal to angle E in triangle DEF) - DE = EF (Two sides of triangle DEF are equal) - BC = EF (The side BC in triangle ABC is equal to the side EF in triangle DEF) ### Step 2: Identify the Type of Triangles Since AB = BC, triangle ABC is an isosceles triangle. Similarly, since DE = EF, triangle DEF is also an isosceles triangle. ### Step 3: Analyze the Angles We know that in triangle ABC: - AB = BC implies that ∠A = ∠C (the angles opposite to the equal sides are equal). In triangle DEF: - DE = EF implies that ∠D = ∠F (the angles opposite to the equal sides are equal). ### Step 4: Compare the Triangles Now we have: - ∠B = ∠E (given) - ∠A = ∠C (from triangle ABC) - ∠D = ∠F (from triangle DEF) ### Step 5: Use the SAS Congruence Criterion We can now apply the SAS (Side-Angle-Side) congruence criterion: - AB = EF (given) - ∠B = ∠E (given) - BC = DE (since BC = EF and DE = EF, we can say BC = DE) Thus, we have two sides and the included angle equal in both triangles: - AB = EF - ∠B = ∠E - BC = DE ### Conclusion By the SAS criterion, triangle ABC is congruent to triangle DEF. Therefore, the correct statement is that both triangles are congruent and isosceles.
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