3.4-3.6 Flashcards
Interior Angle Measures in Polygons Theorem
The sum of the angle measures of an n-gon is given by the formula
S(n) = (n -2)180o
Exterior Angle Measures in Polygons Theorem
The sum of the exterior angle measures of an n-gon, one angle at each vertex, is 360o
regular polygon
iff all its sides r equal in measure & all its angles r = in measure
inscribed
drawn inside the figure
circumscribed
drawn outside the figure
chords
segments whose endpoints are on the circle
Perpendicular Bisector of a Chord Theorem
The perpendicular bisector of a chord of a circle passes through the center of the circle.
central angle
an angle w/ its vertex at the center of the circle
measure of an arc intercepted (cut off) by a central angle is = to the measure of that central angle
minor arc
< 180
can be named w/ 2/3 letters (just remember that a major arc is named w/ 3 letters to distinguish it from a minor arc w/ the same endpts)
semicircle
= 180
named with three letters
outside letters = diameter; Ex: arcSTU → SU is diameter
major arc
180 < arc < 360
named w/ 3 letters
inscribed angle
an angle formed by two chords that intersect at a point ON a circle
intercepted arc
the arc that lies within an inscribed angle
Inscribed Angle Measure Theorem
The measure of an inscribed angle of a circle is equal to half the measure of its intercepted arc.
Inscribed Right Angle Theorem
An inscribed angle whose intercepted arc is a semicircle is a right angle.
