Rhombus Diagonal Properties: Analyzing Triangle Congruence

Rhombus Diagonals with Triangle Congruence

Given the rhombus:

BBBAAACCCDDD

Are the triangles formed by the diagonal congruent?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:03 Are the triangles formed by the rhombus diagonal equal?
00:07 Yes! The diagonal is a side that both triangles share.
00:13 In a rhombus, every side is the same length, so all sides are equal.
00:25 The triangles are congruent by side, side, side.
00:34 And that's how we find the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Given the rhombus:

BBBAAACCCDDD

Are the triangles formed by the diagonal congruent?

2

Step-by-step solution

To determine if the triangles formed by the diagonals of a rhombus are congruent, we proceed with the following analysis:

Step 1: Understanding the properties of a rhombus

  • All sides of a rhombus are of equal length.
  • The diagonals of a rhombus bisect each other at right angles, meaning each diagonal divides the other into two equal parts.
  • The diagonals also form right triangles with each pair of adjacent sides.

Step 2: Applying congruency conditions

Consider the diagonals AC AC and BD BD that intersect at a point E E . The triangles of interest are ABE \triangle ABE , BCE \triangle BCE , CDE \triangle CDE , and DAE \triangle DAE .

Each diagonal is bisected by the other, meaning AE=EC AE = EC and BE=ED BE = ED . Because the diagonals intersect at right angles, each of these triangles is a right triangle.

By the Side-Side-Side (SSS) postulate of congruence:

  • AE=EC AE = EC
  • BE=ED BE = ED
  • The hypotenuse for each set of triangles is a side of the rhombus, which are equal by definition of a rhombus.

Step 3: Conclusion

Thus, all four triangles ABE \triangle ABE , BCE \triangle BCE , CDE \triangle CDE , and DAE \triangle DAE are congruent by SSS postulate, confirming that the triangles formed by the intersection of the diagonals in a rhombus are congruent.

Therefore, the statement that the triangles formed by the diagonals of a rhombus are congruent is True \text{True} .

3

Final Answer

True

Key Points to Remember

Essential concepts to master this topic
  • Property: Rhombus diagonals bisect each other at right angles
  • Technique: Apply SSS congruence with equal sides AB=BC=CD=DA AB = BC = CD = DA
  • Check: All four triangles have same side lengths and right angles ✓

Common Mistakes

Avoid these frequent errors
  • Assuming triangles are congruent without proving it
    Don't just say the triangles look the same = wrong reasoning! Visual similarity doesn't prove congruence. Always use formal congruence postulates (SSS, SAS, ASA) with the specific properties of rhombus diagonals.

Practice Quiz

Test your knowledge with interactive questions

Do the diagonals of the rhombus above intersect each other?

FAQ

Everything you need to know about this question

Why are the diagonals of a rhombus special?

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Rhombus diagonals are unique because they bisect each other at right angles. This creates four right triangles with equal corresponding sides, making congruence easier to prove.

How do I know which triangles to compare?

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The diagonals create four triangles: ABE \triangle ABE , BCE \triangle BCE , CDE \triangle CDE , and DAE \triangle DAE where E is the intersection point. All four are congruent to each other!

What if the rhombus looks like a square?

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A square is a special type of rhombus! The same diagonal properties apply - they still bisect each other at right angles, so the triangles are still congruent.

Can I use a different congruence postulate?

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Yes! You could use SAS (two equal sides from rhombus + right angle) or even ASA if you identify the angles. SSS is often easiest because all sides are clearly equal.

Do I need to measure the actual lengths?

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No! You don't need specific measurements. The properties of a rhombus (all sides equal, diagonals bisect at right angles) are enough to prove congruence algebraically.

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