One of the first things you learn as a toddler is that you can't fit a square peg in a round hole, no matter how hard you try. But as you grow up, you learn about more bewildering and complex shapes that exist in two or three dimensions and often have a bizarre set of physical properties, from a center of gravity in an unexpected location, to the ability to spin in one direction and not the other, to being technically innocent but thoroughly reminiscent of something very naughty indeed.
Some shapes derive their names from Greek or Latin origins, while others are named for the popular toy, tool or symbol that makes use of them. Some appear in everyday life, whether by design (literally) or simply baked into nature's lines in the form of sunflowers and golden ratios. Others are rarer, meaning you might not recall their names - mainly because you don't necessarily need to remember the name of a twelve-sided shape in order to get through your ordinary day. Either way, there was probably a time that you knew all of their correct names, even if just to get yourself through the SAT. So click on through and let's see how much you've retained!
A circle is a two-dimensional shape where the boundary of the circle is always the same distance from its center point. It basically is a line that meets itself. A circle consists of a number of properties, including a circumference, a radius, a diameter, and an area.
A cube is a three-dimensional box shape which is symmetrical and consists of six equal box shapes, all with the same length sides and the same internal and external angles.
This type of triangle has three equal length sides and three equal angles that add up to 180 degrees. Each of the three angles must, therefore, be 60 degrees.
This three-dimensional figure has a hexagon base and then six equal triangles protruding upwards from that base. It also has seven vertices and twelve edges.
An irregular triangle, also called a scalene triangle, has three unequal sides and three unequal angles.
A pentagon is a two-dimension figure with five equal straight sides and five equal internal angles. The angles, when added up, will equal 540 degrees.
Decagons consist of 10 sides. They can be regular, where all sides are of equal length and all angles the same, or irregular, where sides are different lengths and angles inside the decagon vary. Note that whether the decagon is regular or irregular, the angles inside will add up to 1440 degrees.
Also known as a right-angled triangle, this triangle will always have two sides forming a 90 degree angle. The other two can be anything else, but together will always make the other 90 degrees.
Both regular and irregular octagons have eight sides. Unlike a regular octagon where the sides are all equal length, an irregular octagon features irregular sides and angles. The angles, however, will always add up to 1080 degrees.
A hexagon is a six-sided figure with equal sides. The angles inside are each 120 degrees, adding up to a total of 720 degrees. Of course, thats a perfect hexagon. Sides can be of different lengths and angles can change, but they will always add up to 720 degrees.
This two-dimensional shape has opposite sides of equal length. All four internal angle are 90 degrees, adding up to 360 degree in total. To find the area of a rectangle, all you need to do is multiply its width by its height.
A two-dimensional shape that is thinner at the ends where it curves than its middle section. It is often used to describe the moon, but is also found in religion, particularly Islam.
An ellipse is like a circle but differs in the fact that it looks like it has been slightly squished. A circle is considered to be an ellipse.
Simply put, a convex polygon has all its interior angles less than 180 degrees. As soon as one of the angles goes above this number, it becomes a concave polygon. Note that all the vertices of the polygon point away from the center of this two-dimensional object.
This two-dimensional figure consists of four equal sides with four internal angle of 90 degrees. These angles add up to 360 degrees. All opposite sides are also parallel.
An isosceles triangle has two sides of equal length with two equal, internal angles corresponding to those sides. The sides and the angles are sometimes called congruent, which basically is a fancy word for equal.
A parallelogram is a four-sided figure where the two opposite side are parallel. For instance, a square, a rhombus and a rectangle, although all different, are parallelograms.
This three-dimensional shape consists of a circular base. It has a curved surface that reaches up to form a tip. This is known as the apex of the cone.
All quadrilaterals are polygons. When they are irregular, their sides are not the same, unlike a regular polygon where all sides and angles are congruent. The angles, however, will still add up to 360 degrees.
A heptagon is a figure that has seven equal sides and equal angles. It is a polygon and can sometimes be called a septagon.
An obtuse triangle features an angle with more than 90 degrees. Only one side can be obtuse, otherwise the points of the triangle will never meet. If one angle is obtuse, the other two angles can only add up to 90 degrees.
A triangular prism is a three-dimensional object. It consists of three sides that are shaped as rectangles and two bases in the shape of triangles.
Octagons can either be convex or concave. A convex octagon will have all its eight angles pointing in an outwards fashion. None of these angles can be more than 180 degrees in size.
Cylinders are three-dimensional figures with two ends that are either circular or elliptical in shape. These are connected by a curved side.
As with all hexagons, a convex hexagon has six sides. None of it internal angles can exceed 180 degrees. If this happens, the hexagon is concave.
A triangular-based pyramid is a three-dimensional figure that consists of a base and three triangular sides. All of these are generally the same size, although they don't need to be. If they are, the pyramid is called a tetrahedron.
A sphere is a three-dimensional object that is perfectly round or symmetrical. This means that all points on the surface of the sphere are exactly the same distance from its center.
A two-dimensional shapes with five sides. In an irregular pentagon, these sides, and the internal angles they produce, are unequal. The sum of all the angles on a pentagon is 540 degrees.
A scalene triangle, also called an irregular triangle, has three unequal sides and three unequal angles.
A trapezium is a quadrilateral with no parallel sides. This is a U.S. definition. In the U.K., it would be called a trapezoid.
Essentially, a hexagonal prism is an octahedron. It features two bases, hexagonal in nature, and six rectangular sides. It is a three-dimensional shape.
As with all hexagons, a concave hexagon has six sides. It will also have an angle that points back to it. Internal angles can exceed 180 degrees.
An octahedron has eight sides. In its regular form, these are equilateral triangles. Essentially, this three-dimensional figure is two pyramids that are connected by their bases and stand 180 degrees to each other.
A three-dimensional figure, a dodecahedron is a polygon with 12 faces. In the case of a regular dodecahedron, these faces take the form of 12 pentagons. It has 30 edges and 20 vertices.
This quadrilateral has two sides that run parallel to each other. These are often referred to as the bases. The other two sides are not parallel and are called the legs. The distance between the two parallel sides is called the altitude.
A cuboid is a three-dimensional shape where all the angles are 90 degrees formed by six flat sides. Cuboids are actually convex polyhedrons.
This three-dimensional figure has a square base and four equal triangles protruding upwards from that base. It also has five vertices and eight edges.
A two-dimensional object with six sides, a regular hexagon has equal sides and internal angles, where an irregular hexagon will not. The internal angle is often more than 180 degrees, as two sides point back inside the hexagon.
An eight-sided polygon, an octagon in its regular form includes eight equal sides forming eight equal internal angles. If it is an irregular octagon, one or more angles will not be equal.
A concave polygon has two sides forming an internal angle. This also means that the angle is more than 180 degrees. This can only be achieved if the polygon has four sides or more.
An icosahedron has 20 faces. These take the form of equilateral triangles all joined together. This means a icosahedron has 30 sides and 12 vertices. If you look at a section of five of these equilateral triangles, you will see that they form a pentagon.
Nonagons are two-dimensional shapes with nine sides. With a regular nonagon, all sides and internal angles are equal. With an irregular nonagon, sides may not be equal. This produces angles that are not equal and exceed 180 degrees.
A concave octagon has two sides that form an internal angle leading to an irregular shape. This also means the angle is more than 180 degrees when measured.
A two-dimensional shape with 10 sides. In an irregular decagon, these sides, and the internal angles they produce, are unequal. The sum of all the angles in a decagon is 1440 degrees.
This is a solid figure where all plane sections are made from circles or ellipses. The earth is shaped like an ellipsoid, and not a sphere, as was once thought.
A rhombus can be defined in many ways. It is a equilateral, quadrilateral, or a parallelogram with equal sides. To easily recognize one, look for a diamond shape. All sides will be of equal length.
Hepatgons are a form of a polygon but with seven sides. A regular heptagon has equal sides and angles. An irregular heptagon has different length sides and different angles sizes.
This is a 9-sided polygon with nine angles. It is also sometimes called an enneagon. All the angles within a nonagon add up to 1260 degrees.
A two-dimensional shape that has two sides that are pairs. The adjacent sides are also equal in length. All internal angles will always add up to 360 degrees. Two angles where the pairs meet will always be the same .