Short Answer 
The parallelogram JKLM is identified as a rectangle, characterized by right angles and equal opposite sides. Using the SAS postulate, triangles ΔJML and ΔKLM are proven congruent, leading to the conclusion that corresponding sides such as JL and MK are also congruent, confirming the properties of JKLM as a rectangle.
Step 1: Identify Key Properties of the Parallelogram
Firstly, recognize that parallelogram JKLM is defined as a rectangle. This means it possesses certain characteristics such as:
- All interior angles, specifically ∠JML and ∠KLM, are right angles (90°).
- The lengths of opposite sides are equal, indicating JM ‚âÖ KL.
- Self-congruence is verified through the reflexive property, ML ‚âÖ ML.
Step 2: Prove Triangle Congruence Using SAS Postulate
Next, apply the Side-Angle-Side (SAS) postulate to establish that triangles ΔJML and ΔKLM are congruent. This involves:
- Identifying two sides and the included angle in both triangles that are congruent.
- Confirmed congruence: JM ≅ KL, ML ≅ ML, and the angle ∠JML ≅ ∠KLM.
Step 3: Conclude Based on Triangle Congruence
From the established congruence of the triangles, it follows that corresponding parts are also congruent. This leads to the conclusion that:
- JL ‚âÖ MK, as congruent parts of congruent triangles are congruent.
- Thus, reinforcing that parallelogram JKLM indeed has the properties of a rectangle.