Mathematics — first biennium · Lesson
Radius, diameter, chord and tangent describe different relations. A diameter is a chord through the centre; a tangent is perpendicular to the radius at the tangency point.
Prerequisites: Geometric objects and angles
Goal: Recognize centre, radius, diameter, chord, arc, secant and tangent and use their fundamental relations.
In this lesson: Recognize centre, radius, diameter, chord, arc, secant and tangent and use their fundamental relations.
New concept: A circumference and a disk are not the same: the circumference is the set of points at distance r from the centre, while the disk also includes interior points. Radius, diameter, chord and arc describe different parts of the figure.
How to proceed: To classify a segment, first ask whether it passes through the centre. For the tangent, look at the radius ending exactly at the contact point.
You can already assume: Geometric objects and angles.
Circle showing centre, radius, diameter, chord and tangent.
Completed exercises: 0/5 · Correct on first attempt: 0
To classify a segment, first ask whether it passes through the centre. For the tangent, look at the radius ending exactly at the contact point.
Data / situation: The circle has radius 5. In the diagram AB passes through O and line t touches the circle at T.
ConceptStep separates what is required from what is recommended or useful as reinforcement. Only required prerequisites block your progress.
Relationships: solid line = required · dashed line = recommended · dotted line = reinforcement.