Transcript ANGLES and ARCS - Lewiston School District

ANGLES and ARCS
Central Angle - an angle whose
vertex is at the center point and
is formed by two radii.
Sum of Central Angles - the
sum of the measures of the
central angles of a circle is 360.
Arc - a part of the circle.
Minor Arc - less than 180 and
named by two points.
Major Arc - greater than 180 and
less than 360 and named by
three points.
Semicircle - arc with measure of
180, formed by a diameter and
named by three points.
Arc Measures
• Minor Arc is equal to the
measure of its central angle.
• Major Arc is 360 minus the
minor arc.
• Semicircle is formed by a
diameter and is equal to 180.
Arc Addition Postulate
The measure of an arc
formed by two adjacent arcs
is the sum of those two arcs.
• Congruent Circles - have
same radii.
• Congruent Arcs - arcs in a
circle with the same
measure.
• Concentric Circles –
• circles with the same center
point, but have different
radii.