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.