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Find Arc Measures. Lesson 6.2 Page 191. Definitions. Central Angle- and angle whose vertex is the center of the circle. Minor Arc- an arc measure less than 180˚. Major Arc- an arc measure more than 180˚. Measuring Arcs. The measure of a minor arc is equal to its central angle.
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Find Arc Measures Lesson 6.2 Page 191
Definitions • Central Angle- and angle whose vertex is the center of the circle. • Minor Arc- an arc measure less than 180˚. • Major Arc- an arc measure more than 180˚.
Measuring Arcs • The measure of a minor arc is equal to its central angle. • The measure of a major arc is equal to 360˚ - minor arc associated with it.
Find the measure of each arc of P, where RTis a diameter. c. a. RTS RST RS b. a. RSis a minor arc, so mRS=mRPS=110o. b. – RTSis a major arc, so mRTS = 360o 110o = 250o. c. RT is a diameter, so RSTis a semicircle, and mRST=180o. EXAMPLE 1 Find measures of arcs SOLUTION
Survey a. = + A recent survey asked teenagers if they would rather meet a famous musician, athlete, actor, inventor, or other person. The results are shown in the circle graph. Find the indicated arc measures. a. mAC mAB mBC mAC EXAMPLE 2 Find measures of arcs SOLUTION = 29o + 108o = 137o
Survey b. A recent survey asked teenagers if they would rather meet a famous musician, athlete, actor, inventor, or other person. The results are shown in the circle graph. Find the indicated arc measures. mACD = mAC + mCD b. mACD EXAMPLE 2 Find measures of arcs SOLUTION = 137o + 83o = 220o
Survey – mADC = 360o A recent survey asked teenagers if they would rather meet a famous musician, athlete, actor, inventor, or other person. The results are shown in the circle graph. Find the indicated arc measures. c. mAC c. mADC EXAMPLE 2 Find measures of arcs SOLUTION = 360o – 137o = 223o
Survey A recent survey asked teenagers if they would rather meet a famous musician, athlete, actor, inventor, or other person. The results are shown in the circle graph. Find the indicated arc measures. mEBD = 360o – mED d. d. mEBD EXAMPLE 2 Find measures of arcs SOLUTION = 360o – 61o = 299o
for Examples 1 and 2 GUIDED PRACTICE Identify the given arc as a major arc, minor arc, or semicircle, and find the measure of the arc.
1 . TQ TQis a minor arc, so m TQ=120o. 2 . QRT QRTis a major arc, so m QRT=240o. for Examples 1 and 2 GUIDED PRACTICE SOLUTION SOLUTION
3 TQRis a semicircle, so m TQR =180o. 4 . TQR . QS QSis a minor arc, so m QS =160o. for Examples 1 and 2 GUIDED PRACTICE SOLUTION SOLUTION
5 TSis a minor arc, so m TS =80o. 6 . TS . RST RSTis a semicircle, so m RST =180o. for Examples 1 and 2 GUIDED PRACTICE SOLUTION SOLUTION
a. b. a. CDEF because they are in the same circle and mCD = mEF b. RSand TUhave the same measure, but are not congruent because they are arcs of circles that are not congruent. EXAMPLE 3 Identify congruent arcs Tell whether the red arcs are congruent. Explain why or why not. SOLUTION
a. b. a. CDEF because they are in the same circle and mCD = mEF b. RSand TUhave the same measure, but are not congruent because they are arcs of circles that are not congruent. EXAMPLE 3 Identify congruent arcs Tell whether the red arcs are congruent. Explain why or why not. SOLUTION
VXYZ because they are in congruent circles and mVX=mYZ . c. c. EXAMPLE 3 Identify congruent arcs Tell whether the red arcs are congruent. Explain why or why not. SOLUTION
ABCD because they are in congruent circles and mAB=mCD . 7. for Example 3 GUIDED PRACTICE Tell whether the red arcs are congruent. Explain why or why not. SOLUTION
8. MNand PQhave the same measure, but are not congruent because they are arcs of circles that are not congruent. for Example 3 GUIDED PRACTICE Tell whether the red arcs are congruent. Explain why or why not. SOLUTION
Homework 6.2 • Exercise set B page 195 • 1-41 odd