Squares and rectangles become evident in many products. If you look around your house, these shapes are commonly seen in refrigerators, washing machines and stoves. Cardboard boxes also rely on the square and rectangle shape. Bear in mind products do not happen by chance; a product designer has to sit down at a drafting table or computer and actually draw out the shape of every product.
A multitude of products take circular forms, including pots and pans, drinking glasses and cups. This is because a circle makes the most efficient use of space for the intended use of the product. After years of experimentation, designers have concluded that a circle is the best shape to use for a drinking glass. Imagine trying to drink out of a glass with a square top, or cook with a square pan on the stove-top.
A triangle only has three simple straight lines, but this shape has significant implications. Structures made with the triangle shape are very strong, because a triangle does not flex. The triangle is commonly employed in architecture, particularly in bridge trusses and beams.
A parabola looks almost like part of a circle. Think of a parabola as being like a very shallow bowl. Telescope mirrors have a shallow parabola shape on the reflecting surface. This is because the unique feature of a parabola is that it has a central focal point. All faint light beams that reflect off a parabolic telescope mirror eventually come together into the eyepiece; this is why far off stars and planets can be seen.
An oval looks roughly like the shape of the human eye. An oval's shape is actually very complex, having an ever changing, curved surface. Ovals are not used that extensively, but some products have a definite oval shape. Because a United States football has to be thrown, an oval shape is used to make the ball. This is because it has to "fly" through the air with as little resistance as possible.