C5

DEFINITIONS

• The collinear points: are points that are in the same straight. 

• The coplanar points: are points that are in the same plane.

• The intersecting lines: are two lines with a point on common.

• The parallel lines: are lines that are in the same plane and do not intersect.

• The concurrent lines: are three or more coplanar lines that have a point in common.

• A segment AB: is the set of points A and B and of all points between A and B.

• An angle: is the union of two non-collinear segments that have the same endpoint.

• Conjugate Angles: Two or more angles whose sum is 360 degrees

• Supplementary Angles: Two or more angles are supplementary if their sum is 180 degrees.

• Complementary Angles: Two or more angles are complementary if their sum is 90 degrees.

• Vertical angles: are pairs of opposite angles formed when two lines intersect each other at a point. They are thus also known as vertically opposite angles. Any two intersecting lines form two pairs of vertical angles. In geometry, the word ‘vertical’ means ‘related to a vertex’ or corner.

• A triangle: is the union of three segments determined by three noncollinear points.

• A circle: is the set of all points of a plane that are at a fixed distance of a given point of the plane.

THEOREM 1: The sum of the interior angles of the triangles is 180 degrees

THEOREM 2: Vertically opposite angles are congruent 

ACTIVITY 

Which definition corresponds to each of the images?

   

ANGLES

PRACTICE 1

• Convert from degrees to radians the following angles

• Convert from radians to degrees the following angles

• Calculate the value of the angle in degrees and radians in each of the examples and classify them according to their measure

• Find the unknown angle in each case.