ݷʱ : 2024/12/26 2:45:39һ µȫĶ
21. (8)ͼ֪YABCDEBCϵһ㣬ADӳFʹAFCDEC.
(1)֤ıDECFƽıΣ
12
(2)AB13DF14tan ACFij
5
22. (10)ͼ֪ABCУAB=BCAEBCEEFABFCE=2cosAEF=
4BEij. 5
23. (10)ͼˮӵĺΪABCDӶBCΪ6 mӸΪ3.2 mΪˮӵˮҪˮӼӸ2 mұְӶȲ䣬ӭˮCD¶Ȳ䣬DZˮµ¶ԭ1212.5(¶¸µˮƽȵı)ӸߺİӵHDijΪ٣
24. (10)ͼڡABCУCDDZABϵߣBǣsin B=A=
2 tan 21AC=35. 2(1)BĶABֵ (2)tanCDB.
25. (12)ͼACijл·һΣAEBFCDϱĽֵ뻷·ACĽ·ڷֱABCDλڵAıƫ45㷽Bıƫ30㷽ϣAB=2 kmDAC=15.
(1)BD֮ľ룻 (2)CD֮ľ.
ο
1. C 2. B 3. C 4. B 5. A 6. D 7. B 8. A 9. D 10. A 11.
1241
12. 10 13. 14. 25003 15. 16. 2 17. y23x3 18. 533
6-2 466623)22.
2222231331132222
(2)ԭʽ3()()1.
223422422BC20. ⣺RtABCУBC=2A=30㣬AC==23EF=AC=23ΪE=45㣬
tanA19. ⣺(1)ԭʽ2(2
FC=EFsin E=6AF=ACFC=236. 21. (1)֤ıABCDƽıΣADBC.ADEDEC. ֡ߡAFCDECAFCADEDEFC. ıDECFƽıΣ
(2)⣺DDHBCڵHıABCDƽıΣBCDAAB12DH
CD13.֡tan Atan DCHDH12CH5. DF14CE14.EH
5CH9. DE9212215.CFDE15.
22. ⣺ΪAEBCEEFABFԡAEB=AFE=90. ԡBBAE=BAEAEF=90.ԡB=AEF. ΪcosAEF=
44BEcosB=. ΪcosB=55ABAB=BCCE=2BE=4aAB=5aCE=a. a=2.BE=8.
23. ⣺BG3.2 mMNEF3.225.2(m)MENFBC6 mRtDEFУ
EF1MN1
FD2EF25.210.4(m)RtHMNУHN2.5MNFD2HN2.5
13(m)HDHNNFFD13610.429.4(m)ӸߺİӵHDijΪ29.4 m. 24. ⣺(1)CEABECE=xRtACEУΪtan A=
2CE1=AE=2xAE2AC=x2+(2x)=5x5x=35x=3CE=3AE=6. RtBCEУΪsin B=2 2ԡB=45㣬ԡBCEΪֱΣBE=CE=3AB=AEBE=9. (2)ΪCDΪߣBD=tanCDE=
1AB=4.5DE=BDBE=4.53=1.52CE3==2tanCDBֵΪ2. DE1.525. ⣺(1)ãEAD=45㣬FBD=30㣬ԡEAC=EADDAC=45㣫15=60. ΪAEBFCDԡFBC=EAC=60. ΪFBD=30㣬ԡDBC=FBCFBD=30. ΪDBC=DABADBԡADB=15㣬ԡDAB=ADBBD=AB=2. BD֮ľΪ2 km. (2)