Preparing for the Regents Examination Geometry, AK
Preparing for the Regents Examination Geometry, AK
Preparing for the Regents Examination Geometry, AK
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27 1. Common external tangents, −−−<br />
AG and −−−<br />
CM<br />
2. Radii −−−<br />
OA and −−−<br />
OC<br />
3. OAG and OCM are right angles.<br />
4. OAG and OCM are right triangles.<br />
5. −−−<br />
OA −−−<br />
OC<br />
6. Tangents −−−<br />
OM and −−−<br />
OG of circle P<br />
7. −−−<br />
OM −−−<br />
OG (Two tangent segments<br />
drawn from an<br />
external point are<br />
congruent.)<br />
8. OAG OCM (HL HL)<br />
9. −−−<br />
AG −−−<br />
CM (CPCTC)<br />
28 1. Circles A and B are congruent with<br />
tangent FG .<br />
2. −−<br />
AF is <strong>the</strong> radius of A. −−<br />
BG is <strong>the</strong> radius of<br />
B.<br />
3. −−<br />
AF −−<br />
BG<br />
4. AFC and BGC are right angles.<br />
5. FCA GCB<br />
6. FCA GCB (AAS AAS)<br />
7. −−<br />
AC −−<br />
BC<br />
29 mA 1 _ (<br />
2 CD BE ). 2(mA) <br />
mCOD mBOE. But mBOE mA.<br />
2(mA) mCOD mA. There<strong>for</strong>e,<br />
3(mA) mCOD.<br />
30 1. −−<br />
AB is tangent to O at E; −−−<br />
CD is tangent to<br />
O at F.<br />
2. −−<br />
OE OF<br />
3. −−−<br />
OA −−−<br />
OC ; −−<br />
OB −−−<br />
OD<br />
4. −−<br />
OE −−<br />
AB<br />
5. OEA and OEB are right angles.<br />
6. −−<br />
OF −−−<br />
CD<br />
7. OFC and OFD are right angles.<br />
8. OEA OFC (HL HL)<br />
OEB OFD<br />
9. −−<br />
AE −−<br />
EB (Addition<br />
−−<br />
CF −−<br />
FD postulate)<br />
or −−<br />
AB −−−<br />
CD<br />
13-5 Angles Formed by<br />
Tangents, Chords, and<br />
Secants<br />
(pages 368–371)<br />
1 (2) 96<br />
2 (1) 24<br />
3 (2) 144<br />
82 Chapter 13: <strong>Geometry</strong> of <strong>the</strong> Circle<br />
4 (4) 173<br />
5 (1) 38<br />
6 (1) 90<br />
7 a 40 b 62 c 225 d 45<br />
e 75 f 100 g 80 h 30<br />
8 a 79 b 38<br />
c x 50, y 60, z 120<br />
9 a 66 b 80 c 73<br />
d 130 e 33 f 73<br />
10 a 90 b 120 c 90 d 60<br />
e 30 f 60 g 30 h 90<br />
11 a 120 b 40 c 80<br />
d 40 e 140 f 100<br />
12 BC CD because in a regular hexagon,<br />
congruent chords subtend congruent arcs.<br />
Chords and a tangent that intercept congruent<br />
arcs are parallel. There<strong>for</strong>e, PC −−<br />
BD<br />
Note: Since <strong>the</strong>re are many variations of proofs,<br />
<strong>the</strong> following is simply one set of acceptable<br />
statements to complete each proof. Depending<br />
on <strong>the</strong> textbook used, <strong>the</strong> wording and <strong>for</strong>mat<br />
of reasons may differ, so <strong>the</strong>y have not been<br />
supplied <strong>for</strong> <strong>the</strong> method of congruence applied<br />
in each problem. (These solutions are intended<br />
to be used as a guide—o<strong>the</strong>r possible solutions<br />
may vary.)<br />
13 1. −−<br />
FB −−<br />
EC<br />
2. BEC EBF<br />
3. EHJ BHG<br />
4. EHJ BHG<br />
(Alternate interior angles<br />
are congruent.)<br />
5. BH _ <br />
HE<br />
HG _<br />
HJ<br />
(Corresponding sides<br />
of similar triangles are<br />
in proportion.)<br />
6. BH JH (The product of means<br />
HE HG equals <strong>the</strong> product of<br />
14 1.<br />
extremes.)<br />
−−<br />
BA −−−<br />
DA<br />
2. Diameter −−−<br />
DC<br />
3. BAD and DBC are right angles.<br />
4. −−<br />
AB is tangent to O at B.<br />
5. mDBA 1 _ m<br />
2 BD<br />
6. mDCB 1 _ m<br />
2 BD<br />
7. mDBA mDCB<br />
8. DBA DCB<br />
9. DBA DCB