Problem #3: Rectangular Parallelpiped

Problem 3. Parallelepiped

Find the diagonal of a rectangular parallelepiped of which the length, the width, and the height are known.

I got excited when I read this problem, I felt that it was one I could really tackle. I drew myself a picture of a parallelepiped (once I looked it up, I honestly I no idea what it was) and drew the diagonal. I realized that I could make a right triangle using the parallelepiped faces and sides where the diagonal is the hypotenuse. Since one of the sides of the triangle is the top face of the shape, I redrew that and found the diagonal of the rectangle.

The other side of the main triangle is the height, so plugging that into the Pythagorean Theorem, I got that the diagonal is the square root of the sum of the width squared, height squared and length squared.