Today we'll dive into the fascinating world of rectangles. A rectangle is a special kind of parallelogram where all angles are right angles, which means they measure 90 degrees. Can anyone tell me why this is significant?

Exactly! And because there are four right angles, the sum of all angles is 360 degrees. To help us remember, we can use the acronym ‘RAMP’ for Right Angles Mean Parallel. This denotes that rectangles, as parallelograms, also have opposite sides that are parallel and equal in length.

Correct! Now, let’s summarize key properties of a rectangle: All angles are 90 degrees, opposite sides are equal, and the diagonals bisect each other. Let’s ensure we grasp these properties. How many degrees are in each angle?

Great! Now, let’s move on to the properties of the diagonals.

Let’s discuss the diagonals of rectangles. What do we know about the diagonals in rectangles specifically?

Exactly! In contrast to general parallelograms, rectangles have equal diagonals. Why do you think that’s important?

Well said! We can use the Right Triangle Congruence Postulate to show this. By splitting a rectangle into two triangles using one diagonal, we achieve congruent triangles, validating the equality of the diagonals. Can you think of examples of where we might find rectangles in real life?

Let's conclude this session by remembering: A rectangle ensures equal diagonals and can be a key structure in everyday objects. Now, let's go over some exercises involving rectangles.

Now that we understand the properties of rectangles, let’s work on some exercises. For instance, if we know the lengths of the two sides of a rectangle are 5 cm and 12 cm, what is the perimeter?

Correct! And if we were to find the area, how would we do that?

Absolutely right! Now let’s try a quick self-check. What would happen if one angle deviates from 90 degrees in a rectangle? What shape would we have instead?

Right! Fantastic participation everyone. Remember these properties as they form the foundation of many geometric principles!