Mathematics is a branch of science. Many scientists consider mathematics a pure science, one that is equal parts precision and imagination. Collinear points is a fancy, but a precise, way of describing points in a line.
Mathematicians use words very exactly. In Euclidean geometry, Collinear points are points that all lie in the same line, whether they are close together, far apart, or form a ray, line segment, or line. A little Latin helps: col + linear = collinear.
The combination, collinear, means points together on a single line.
Anytime you have a series of individual items in a single straight line, you have models of collinear points. Suppose you have eggs in a carton; each egg in one row is a collinear point:
Students seated at a long cafeteria table are collinear. Football players on the line of scrimmage are collinear. Rings on a shower curtain, plants in one row in a garden, numbers on a ruler, moviegoers in a ticket line, and commuters seated on a train are collinear.
For real-life examples to be good models of collinear points, you need to be able to draw a straight line through them. Think of the individual kernels on one row of an ear of corn.
Collinear foods are found all over the globe. In Japan, people enjoy Dango; sweet little dumplings arranged three to five on a skewer.
Sosatie is a South African dish of little cubes of lamb or mutton interspersed with dried apricots, red onions, and mixed peppers, all on skewers.
Frigărui, a Romanian kebab, is cubes of meat with bacon, onions, tomatoes, bell peppers, and mushrooms.
In all cases, the little bits of food are lined up on a bamboo or wood skewer, so they are all points on a single line. They are all collinear.
What is not a model of collinear points? The angle marks around the curved edge of a protractor, for one thing. Neither are spirals, helixes, all five corners of a pentagon, or points on a globe.
Here are some examples of non-collinear points:
Non-collinear points are a set of points that do not lie on the same line. Picture a sushi roll in front of you. Sticking with our example above, a second skewer of food sitting next to ours would not have any points collinear with our skewer, since they are all on a different skewer or line.
Points must lie on the same line to have collinearity. If picture a right triangle with two points label on two different sides points L and R. If point L on the hypotenuse and point R on the base, then point L and point R are non-collinear.
Very often, collinear points appear in geometric figures such as quadrilaterals, triangles, parallelograms, and more. Take this kite with two diagonals intersecting at :
Two sets of collinear points appear around the diagonals in this geometric figure:
But you can also find all these other collinear points since only two points determine a line:
We will leave you with a side view of a little street brazier for making skewered meat kebabs. Notice the legs cross and have a bottom brace, which creates two triangles to keep the brazier stable. Can you find at least sets of collinear points?
We are sure you saw sets like points and , and , and points , but did you also pick up on ones like and ?
The points and , which form two sides of a triangle (the bottom triangle) are also collinear.
Look at points and . Each of these three points are collinear as well. Keep looking; more sets of collinear points are waiting to be found!
We now know that collinear points, sometimes spelled "colinear" (just on L), are points that lie on a straight line. But what about coplanar points? In a three dimensional world, coplanar points are a set of points that lie on the same plane. Learn more about coplanar points.
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