Real-Life Math -- Solution
These corner walls are both 12 feet high and 20 feet long. They join at a 90-degree angle. How can you plan for straight walls?
The corner forms 2 sides of a triangle. The Pythagorean theorem states that a relationship exists between the squares of the sides of a right plane triangle. The sum of the squares of the 2 sides adjacent to the right angle is always exactly equal to the square of the side opposite the right angle, the hypotenuse.
To use the Pythagorean theorem, you will use a fraction of the 20-foot wall. Let us say, one quarter, or 5 feet.
Using your tape measure, and starting at the corner, make a mark at the 5-foot point on each wall. Then, stretch the tape from the 2 5-foot marker points so as to measure the distance between them. This is the hypotenuse. Note the measurement.
Now you must determine what the distance should be.
Take the square of 5 feet:
5 x 5 = 25
The sum of the square of the 2 sides is:
25 + 25 = 50
Therefore, the square of the hypotenuse is 50. Using your calculator, you determine that the square root of 50 is 7.1.
Compare the measure you found using your tape measure. If it is 7.1, the walls are straight. It if is less or more, you will need to make adjustments.
"I use the Pythagorean theorem all the time to be sure that walls are straight," says Reggie Bullard, a self-employed plasterer. "I also use mathematics to calculate the amount of supplies I will need for the space to be plastered."