The Proudest Triangle - Ronald Citron - Bog

The purpose of this book is to teach the basic geometric shapes and how some of them can be combined or altered to make other shapes. For example, the square can be stretched to make the rectangle. The circle can be stretched to make the oval. In essence, the rectangle and square are part of the same set of shapes. This shape is known as a parallelepiped which contains four sides with two sets of opposite parallel sides. When the two sets are of the same length and at right angles (90 degree angles) to each other, the result is a square. When two of the sides are of equal length but longer than the other two sides the result is a rectangle. The circle and oval are both from the set of shapes called the ellipse. When a line passing through the center of the ellipse is of the same length no matter the angle, the result is a circle and the line is called the diameter. Half of the diameter is called the radius - plural being radii. When two lines pass through the center and one line is longer in a direction perpendicular (90 degree angle) to the other line, the result is an oval - one direction is longer than the other. When the circle separates into pie pieces, the technical term for a pie piece is a sector. A sector is made up of two radii of the circle and the curved outer segment. For simplicity, the resulting shapes are kept to a minimum. The purpose is to teach the basics in a fun manner and not to overwhelm the child.