Chapter 12.3, Problem 1E

To determine

To explain:

Thean angle formed by two sides of the given parts.

Explanation of Solution

Given:

The two triangle

  $\Delta EDF\cong \Delta GHI$

Concept used:

Two geometric figures are congruent if a rigid motion or a composition of rigid motions maps one of the figures onto other.

Calculation:

If two triangles are congruent.

So all the corresponding parts are congruent.

If all corresponding parts of two triangles are congruent.

So the triangle are congruent.

  $\begin{array}{l}\angle D\cong \angle H\\ DE\cong HI\\ DF\left|\right|HG\\ \angle DFE\simeq \angle HGI\\ \Delta DFE\cong \Delta HGI\end{array}$

Therefore,

The included angle of two sides of a triangle is the angle formed by the two sides