Check using the Pythagorean theorem: - Redraw

Understanding the Context

What Is the Pythagorean Theorem?

The Pythagorean Theorem states that in a right triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides. Mathematically, it’s expressed as:

> a² + b² = c²

Where:

• a and b are the lengths of the legs (the two shorter sides)
  
• c is the length of the hypotenuse (the longest side)

Key Insights

How to Use the Theorem to Check for a Right Angle

One practical application of the Pythagorean Theorem isn’t just solving triangle problems — it’s verifying whether a triangle is right-angled. This technique is especially useful in fields like surveying, construction, and GPS technology.

Here’s how it works:

1. Identify the triangle sides
   Look at a triangle where you suspect or know one angle might be 90 degrees (a right angle). Let the sides be labeled as follows:
   
   • Side a: one leg
     
   • Side b: the other leg
     
   • Side c: the longest side (potential hypotenuse)

Final Thoughts

2. Square each side length
   Compute a², b², and c² using simple multiplication. It’s easiest to work with whole numbers or fractions, but modern calculators or software handle decimals effortlessly.

3. Check the equation
   Add the squares of the two shorter sides (a² + b²) and compare the result to the square of the longest side (c²).

• ✅ If a² + b² = c², the triangle is right-angled.
  
  • ❌ If the equality does not hold, the triangle does not form a right angle.

Real-World Example

Let’s say you’re an architect double-checking a corner of a room that should be square (90°). You measure three sides: