Table of Contents
Plane Geometric Figures
A plane geometric figure is a shape that can be drawn on a piece of paper without lifting the pen. There are three main types of plane geometric figures: polygons, circles, and ellipses.
A polygon is a shape made up of straight lines. The most common polygon is a rectangle, which is made up of four straight lines. Other polygons include triangles, squares, and hexagons.
A circle is a shape that is made up of all points that are the same distance from a fixed point, called the center of the circle. The distance from the center to any point on the circle is called the radius.
An ellipse is a shape that is like a stretched-out circle. It is made up of all points that are the same distance from two fixed points, called the foci of the ellipse. The distance from one focus to the other is called the focal length.
Examples of Plane Geometry
Plane geometry is the study of flat shapes, such as lines, circles, and triangles. It is simpler than other types of geometry, because it only considers shapes that are two-dimensional.
One example of plane geometry is constructing a line segment between two points. This can be done using a straight edge and a compass. The straight edge is used to draw a line between the two points, and the compass is used to draw a circle around one of the points. The point where the line and the circle intersect is the location of the desired line segment.
Another example is drawing a circle. This can be done by drawing two intersecting lines and then drawing a circle around the point where they intersect.
Important Terminologies in Plane Geometry
In plane geometry, important terminologies are points, lines, angles, and planes.
Points are the most basic elements in geometry. They are simply defined as locations in space. Lines are made up of points and are defined as the path that a point travels along. Angles are formed by two lines intersecting and are measured in degrees. Planes are flat, two-dimensional surfaces that extend in all directions.
Plane Angle in Geometry
In geometry, a plane angle is the angle between two intersecting planes. A plane angle is measured in degrees, with 0 degrees being the angle between the planes that are perpendicular to each other, and 180 degrees being the angle between the planes that are parallel to each other.
Types of Plane Angle
There are three types of plane angle: acute, right, and obtuse.
An acute angle is less than 90 degrees.
A right angle is 90 degrees.
An obtuse angle is greater than 90 degrees.
Plane Angle Formula
\(\theta\) = the angle in radians
\(x\) = the horizontal distance from the starting point to the point on the plane
\(y\) = the vertical distance from the starting point to the point on the plane
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