MATHEMATICS M-1

• Geometry was derived from two Greek words, geo which means earth

  and metron means measurement.
• The undefined terms in Geometry are point, line, and plane
• POINT. It is the most basic term that builds up geometric concept. All other

  geometric figures are collection of points. It has no dimension –
• LINE. It has infinite length extended in both directions, no width nor thickness.
• PLANE. It is flat surface that extends endlessly in all directions. It has length

  and width but no thickness.
• collinear points are points that lie on the same line.
• non-collinear points are points that do not lie on the same line.
• coplanar points are points that lie on the same plane.
• non-coplanar points are points that do not lie on the same plane.
• LINE SEGMENT. It is part of a line with two distinct endpoints.
• RAY. It is part of a line with one endpoint and extends infinitely in one direction.

  A ray is named with its endpoint followed by another point on the ray.
• INTERSECTING LINES. Lines on the same plane and intersect at a common

  point.
• PERPENDICULAR LINES. Two lines are perpendicular if they intersect to

  form right angles.
• PARALLEL LINES. Parallel lines are coplanar lines that DO NOT intersect.
• SKEW LINES. Noncoplanar lines that DO NOT intersect
• It is defined as a figure formed when two rays share a common endpoint

  called the vertex while the rays are referred to as the sides of the angle.
• Acute angle

  -an angle whose measure is less than

  90° but greater than 0°.

  x < 90°
• Right angle

  • an angle whose measure is equal to

  90°.

  x = 90°
• Obtuse angle

  • an angle whose measure is less than

  180° but greater than 90°.

  90°< x < 180°