Rectangle Triangles
1. **Problem Statement:**
Given rectangle JKLM with vertices J (top-left), K (top-right), L (bottom-right), and M (bottom-left), and a diagonal JL drawn.
(i) Name two triangles which are congruent.
(ii) Prove the congruence of these triangles.
2. **Identifying the triangles:**
The diagonal JL divides the rectangle into two triangles: \(\triangle JKL\) and \(\triangle JLM\).
3. **Properties of a rectangle:**
- Opposite sides are equal and parallel.
- All angles are right angles (90 degrees).
- Diagonals are equal in length.
4. **Triangles to consider:**
- \(\triangle JKL\) with vertices J, K, L.
- \(\triangle JLM\) with vertices J, L, M.
5. **Proving congruence:**
We will prove \(\triangle JKL \cong \triangle JLM\) using the Side-Angle-Side (SAS) criterion.
6. **Step-by-step proof:**
- Side JL is common to both triangles.
- Side JK is equal to side LM because opposite sides of a rectangle are equal.
- Angle JKL and angle JLM are right angles (90 degrees) because all angles in a rectangle are right angles.
7. **Applying SAS criterion:**
- Side JK = Side LM
- Angle at K = Angle at M = 90 degrees
- Side JL common
Therefore, \(\triangle JKL \cong \triangle JLM\) by SAS congruence.
**Final answer:**
(i) The two congruent triangles are \(\triangle JKL\) and \(\triangle JLM\).
(ii) They are congruent by SAS criterion: two sides and the included angle are equal.