you are hanging a picture. the picture is level but the walls look off slightly. you want to know if the corners of the wall are squares to see if that's why things don't look right. explain how you could algebraically determine whether or not the corners of the wall are square (right angles)

If you are looking for a square...

You know that you need to have the top and bottom the same length, and parallel. As well as each side the same length and parallel : )
You could also start at the corner of the wall...use a tape measure and measure 3 feet out from the wall (mark it with a piece of tape), then go back to the corner of the wall and measure four feet up the wall, mark it with a piece of tape. Then take the tape measure and check if the hypotenuse of the triangle that you just created is 5 feet long. The first Pythagorean triple is a 3, 4, 5 triple, and if your wall is 90 degrees the hypotenuse will be 5 feet : )

To algebraically determine whether or not the corners of the wall form right angles (squares), you can use the concept of slopes. Here's how you can approach it:

1. Choose any two adjacent walls to analyze, for example, Wall A and Wall B. These walls should share a corner.

2. Measure the height and width of the picture hanging on the wall accurately.

3. Start by assuming the corner formed by the walls is a right angle (square). This means that the slopes of the two walls will be perpendicular to each other, forming a product of -1.

4. Using the slope formula (m = (y2 - y1) / (x2 - x1)), calculate the slopes of Wall A and Wall B separately. Choose two points on each wall to calculate the slope.

5. Multiply the two slopes together. If the product is -1 (or very close to it, considering measurement accuracy), it indicates that the walls form right angles at the corner.

6. Repeat this process for each adjacent pair of walls to check all the corners.

If all the products are close to -1, then the corners are likely square. However, if any of the corners have a significantly different product, it suggests that the walls are not forming right angles.

Keep in mind that this method assumes the walls are straight and the measurements are accurate. Additionally, other factors like construction errors or the structure itself may affect the accuracy of this method, so it's always good to visually confirm as well.