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CIRCLES (G.11A/10.6)
OBJ: SWB INTRODUCED TO BASIC TERMINOLOGY OF CIRCLES. SWBAT FIND THE MEASURES OF CENTRAL ANGLES, ARCS, ARC
LENGTHS AND CIRCUMFERENCE (G.11B,C)WU: SOL questions G.7-GRADED!!!!
**hw/hw log/wkb p. 271circle foldable/Storybook “Circles”
Homework (day 53): wkb p. 271-272 (omit 18, 23-
25)Bring Graph Paper to class!
Pearsonsuccess.net (due Friday)
PRACTICE: PARTS OF CIRCLE
C
F
E
A BP
Circle: ______P
Radius: ____ Diameter: ____Chord:____
Identify a special chord:____
Secant: ____
Minor Arc: ____Major Arc: ____ Central Angle:
____Semicircle: ____
*** Foldable: “Important Parts of a Circle”
Tangent line: _______ Pt of tangency: _____
Sector : ____
Arc: ____
K
GEOMETRIC FIGURES CAN HELP YOU FIND THE CIRCUMFERENCE OF A CIRCLE
Is the rectangle inscribed or circumscribed in the circle?
Find the exact circumference of P. P12
x4
3
The diameter = __________the exact circumference = _______
the approximate circumference = _______(to the nearest tenth)
5
What word refers to the outside of a polygon?What word refers to the distance around a circle?
Another way to measure an arc is by its length. Since an
arch is a part of a circle, its length is PART of thecircumference…..called the ARC LENGTH
Find the length of XY. Leave your answer in term of π. Y
X
16 in Circle Foldable: “Central Angle”
THM: IN THE SAME OR CONGRUENT CIRCLES, TWO ARCS ARE CONGRUENT IFF THEIR CORRESPONDING ANGLES ARE CONGRUENT.
Adjacent Arcs: two arcs in the same circle that have exactly one point in common.
***You can add the measures of adjacent arc just like you add the measures of adjacent angles.
Arc Addition Postulate: mABC = mAB + mBCP
C
B
A
ARC: Is a part of a circle
A) SEMI – CIRCLE (Half a circle) = 180° TRS is a semi-circle mTRS is 180°
B) MINOR ARC: shorter than a semi-circle RS is a minor arc mRS = m∠RPS
SP
T
R
P
SR 60°
60°**** The measure of a minor arc = the measure of its central angle.
C) Major Arc: Larger than a semi-circle RTS is a major arc mRTS = 360 – mRS***The measure of a major arc is: 360 – the measure of its related minor arc.
P
SR
T
DEFINITIONSRadius:
is a segment w/one endpoint at the center of the circle and the other endpoint on the circle.
(All radii of a circle are congruent)
Chords:are segments that have both their endpoints on the circle. (from one side of the circle to the other.)
Diameter:a chord that goes through the center of a circle.