Question

△ abc ≅ △ edc
if m∠ acb = 45°, ab = 10
then m∠ ecd = ? °

Explanation:

Step1: Recall Congruent Triangles

Since $\triangle ABC \cong \triangle EDC$, corresponding angles are equal.

Step2: Identify Corresponding Angles

$\angle ACB$ and $\angle ECD$ are corresponding angles in congruent triangles. So $m\angle ECD = m\angle ACB$.

Step3: Substitute the Given Value

Given $m\angle ACB = 45^\circ$, thus $m\angle ECD = 45^\circ$.

Answer:

45