Unit 2: Lesson 2: Points, Lines, and Flashcards
What is an angle
the figure formed by two lines extending from the same point
What is an arc?
a part of the circumference of a circle or other curve
What is a parallel line
a straight line that always remains the same distance from another line and, therefore, never intersects it
What is a circle?
a closed plane curve with every point on the curve equidistant from a fixed point within the curve
What is a line
a straight figure that has no thickness and extends infinitely in two opposite directions
What is a line segment
the finite section of a line between two points on that line
What is a perpendicular line
a line that intersects another line at a 90 degree angle
What is a point
– a geometric element that has zero dimensions and a location determinable by an ordered set of coordinates
What are angles made of
Angles are made of two intersecting lines and share a common point.
What do angles measure
Angles measure the space between two intersecting lines and are measured in degrees.
Measuring an angle allows you to see what
Measuring an angle allows you to see how far apart two objects are.
What are the four undefined notions in geometry?
The undefined notions in geometry are point, line, distance along a line, and distance around a circular arc.
“The set of all points that are equidistant from a central point” is the precise definition of which key concept?
It is the precise definition of a circle.
conjecture
a statement that is made based on observations but is not yet proven
definition
a statement that determines the meaning of a term or concept and describes what it is
Euclidean geometry
the geometry based on Euclid’s axioms
postulate
a statement that is accepted as true and has not been proved
theorem
a statement that has been proved to be true using arguments and facts that are accepted as true
undefined term
a term that does not need to be defined because it is explained using examples and descriptions, such as point, line, plane, and space
undefined terms examples
point
line
plane
space
