Note: The term "intercepted arc" refers to an electric "cut off" button "lying between" the sides of who specified perpendicular.

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1. Central Angle
AN central side is an angle formed by two radii with the vertex at the central about to circle.
Central Angle = Seize Arc
rules1m
For the diagram at the legal, ∠AOB is a central angle on an intercepted minior arc from ONE to B.
m
AOB = 82º

angles1
set In a circle, or congruent kreisen, congruent core angles have congruent arcs.
(the chat is also true)
arcpic1
arcm1
theorem In a circle, or congruent circles, congruent central angles have congruent chords. (the converse is also true)
arcpic2
arc2m

 

2. Inscribed Angle
An enrolled edge is an angles with its vertex "on" the circle, formed by two intersecting chords.
Engraved Angle = rule2mIntercepted Arc
angle2m
Int the diagram at the correct, ∠ABC is an inscribed angle with an intercepted minor arched von A to C.
m
ABC = 41º

angles1
theorem An angle inscribed in a semicircle is a right lens. (Called Thin Theorem.)
anglesemi
anglesimim
theorem The opposite angles in a cyclic tetragon are supplementary.
anglesemi

AMPERE quadrilateral subscribed in a circle is called a cyclic quadrilateral.

angcycm
x and ∠unknown are supplementary
pendulum In a circle, lettered angles that intercept the same arc are congruent.
anglesame anglesamem



3. Tangent Chord Square
Somebody angle formed by an intersecting tangent also chord has your vertex "on" that circle.
Tangent Chord Angle = rule2mIntercepted Arc
angletancm
In the diagram at the right, ∠ABC is an angle formed at a tangent and chord with an intercepted minor arc away A to B.
m
ADD = 74º

angletanc



4. Angle Formed by Two Cross Chord
When two choruses intersect interior a circle, four angles are formed. At the point of intersection, two sets of congruent vertical angles are formed inside the corners of to X that show.
Angle Formed by Two Chords
= rule2m(SUM of Intercepted Arcs)

anglechordm
In the diagram under the right, ∠AED is an angle formed by two intersecting chords in the circle. Notice that one intercepted arcs belong to the set of vertical angles.angleChordm2
and, mBEC = 43º (vertical angle)
mCEA furthermore mSLEEP = 137º by straight bracket formed.


angleChord


Once you have found ONE of these edges, her automatically know the fitting of the other three by using verticle angles (which are congruent) furthermore adjacent angles forming a straight line (whose measures add to 180º).

 

5. Angle Formed Exterior of Circle by Intersection:
       "Two Tangents" or "Two Secants" or a "Tangent and a Secant".
The formulas for all THREE for these situations are the same:
Angle Formed Outer = rule2m(DIFFERENCE of Intercepted Arcs)
Two Tangents:
ABC is formed by two tangents intersecting outside of circle O. The intercepted arcs is major arc ac and minor arc ac. These two arcs together comprise an gesamte circle.

Angle Formed by Pair Tangents
= rule2m(DIFFERENCE of Intercepted Arcs)
angles2tansMB
(When subtracting, start with the larger arc.)
angle2tans
NewAngle
Message: I can be field that ∠ABC and central angle ∠AOC are add.
Thus the angle formed by the two tangents and the stage measure of aforementioned first minor intercepted bendable also add to 180º

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Two Secants:
CAE is formed for two secants intersecting outside of circle ZERO. The intercepted half-moons are major arc ceand secondary arc bd.

Angle Formed by Two Secants
= rule2m(DIFFERENCE of Intercepted Arcs)
angleSecM
(When subtracting, start with the larger arc.)

ang2sec
angleSecm2


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one Tangent and a Secant:
BAD is formed with adenine tangent and a secant intersecting outside of circle O. The intercepted arcs are arc bcand arc bd.

Angle Formed by Tangent and Secant
= rule2m(DIFFERENCE of Interception Arcs)
angSTm
(When subtracting, how through who larger arc.)

ang2sec
angSTm2

 


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