An angle that measures exactly 180 degrees, appearing as a straight line.
straight angle
The distance from the center of a circle to any point on its edge; it is half the diameter.
radius
An angle that measures exactly 90 degrees, forming a perfect corner.
right angle
A closed shape made up of straight lines, with at least three sides, such as triangles and squares.
polygons
A part of a line that has one endpoint and extends infinitely in one direction.
ray
A straight line that passes through the center of a circle and connects two points on its edge; it is twice the length of the radius.
diameter
Lines that run side by side and never intersect, no matter how far they are extended.
Parallel lines
An angle that measures 0 degrees, meaning there is no space between the two rays
zero angle
An angle that measures less than 90 degrees; it is sharper and smaller than a right angle.
acute angle
A round shape where all points are the same distance from the center point; it has no corners.
circle
An angle that measures more than 90 degrees but less than 180 degrees; it is wider than a right angle.
obtuse angle
A type of polygon that has four sides, such as squares and rectangles.
Quadrilateral
A tool used to measure angles in degrees
protractor
A part of a line that has two endpoints and is a fixed length.
line segment
Lines that intersect at a right angle (90 degrees).
Perpendicular Lines