MICRO LESSON 1
Parts of a Circle
Picture it:
A circle is all points at equal distance from a centre.
Simple:
Radius joins centre to circle; diameter passes through centre.
Example:
Wheel hub and rim.
Quick Check:
How many radii make a diameter?
MICRO LESSON 2
Chord
Picture it:
A chord joins two points on a circle.
Simple:
Diameter is the longest chord.
Example:
A straight line across the circle.
Quick Check:
Is every chord a diameter?
MICRO LESSON 3
Equal Chords
Picture it:
Equal chords subtend equal angles at the centre.
Simple:
The reverse is also true.
Example:
Same chord length gives same central angle.
Quick Check:
What does an equal central angle imply?
MICRO LESSON 4
Perpendicular from Centre
Picture it:
A perpendicular from centre to a chord bisects it.
Simple:
It cuts the chord into equal halves.
Example:
Centre-drop to chord.
Quick Check:
What does it bisect?
MICRO LESSON 5
Angle at Centre and Circle
Picture it:
The angle at centre is twice angle at remaining circumference on same arc.
Simple:
Central angle = 2× inscribed angle.
Example:
100° at centre gives 50° at circle.
Quick Check:
If inscribed angle 35°, central?
MICRO LESSON 6
Angles in Same Segment
Picture it:
Angles subtended by same chord in same segment are equal.
Simple:
They stand on the same arc.
Example:
Two observers on same arc see same angle.
Quick Check:
When are such angles equal?
MICRO LESSON 7
Cyclic Quadrilateral
Picture it:
A quadrilateral with all vertices on a circle is cyclic.
Simple:
Opposite angles sum to 180°.
Example:
110° opposite 70°.
Quick Check:
If one angle 95°, opposite?
MICRO LESSON 8
Arc and Sector
Picture it:
An arc is part of circumference; a sector is region between two radii and arc.
Simple:
Think pizza slice.
Example:
Minor and major arcs.
Quick Check:
Which is a region?