The TV screen's diagonal
A TV is advertised by its diagonal, but the box lists width and height. The diagonal, width, and height form a right triangle, so a² + b² = c² turns the two sides you can measure into the screen size on the label.
a² + b² = c²
In any right triangle, the square of the hypotenuse (the side opposite the right angle, and the longest) equals the sum of the squares of the other two sides: a² + b² = c². This lets you find a missing side whenever you know the other two.
The hypotenuse is c
Always assign c to the side across from the 90° angle. The two shorter legs are a and b, and their order doesn't matter.
Legs 3 and 4: c² = 3² + 4² = 9 + 16 = 25, so c = 5. The classic 3-4-5 right triangle.
Lab · Find the hypotenuse
- A right triangle has legs of length 6 and 8.
- Square each leg and add them.
- Take the square root to find c.
What you should see: 6² + 8² = 36 + 64 = 100, so c = √100 = 10.