3.4-3.6 Flashcards Preview

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Flashcards in 3.4-3.6 Deck (19)
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1

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

2

Exterior Angle Measures in Polygons Theorem

The sum of the exterior angle measures of an n-gon, one angle at each vertex, is 360o

3

regular polygon

iff all its sides r equal in measure & all its angles r = in measure

4

inscribed

drawn inside the figure

5

circumscribed

drawn outside the figure

6

chords

segments whose endpoints are on the circle

7

Perpendicular Bisector of a Chord Theorem

The perpendicular bisector of a chord of a circle passes through the center of the circle.

8

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

9

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)

10

semicircle

= 180

named with three letters

outside letters = diameter; Ex: arcSTU → SU is diameter

11

major arc

180 < arc < 360

named w/ 3 letters 

12

inscribed angle

an angle formed by two chords that intersect at a point ON a circle

13

intercepted arc

the arc that lies within an inscribed angle

14

Inscribed Angle Measure Theorem

The measure of an inscribed angle of a circle is equal to half the measure of its intercepted arc.

15

Inscribed Right Angle Theorem

An inscribed angle whose intercepted arc is a semicircle is a right angle.

16

Equal Inscribed Angles Theorem

If 2 inscribed angles in the same circle intercept the same arc, then they are equal in measure.

17

Intersecting Chords Theorem

The measure of an angle formed by 2 chords that intersect inside a circle is equal to half the sum of the measures of the intercepted arcs.

.5 (a + b)

18

Secants & Tangents Theorem

The measure of an angle formed by 2 secants, 2 tangents, or a secant & a tangent drawn from a point outside a circle is equal to half the difference of the measures of the intercepted arcs.

.5 (big - small)

19

tips for finding angles

continue radius to diameter

use systems of equations

remember perpendicular rule