在 中,由已知条件解三角形,其中有两解的是( ) A. B. C. D
在中,由已知条件解三角形,其中有两解的是()A.B.C.D....
在 中,由已知条件解三角形,其中有两解的是( ) A. B. C. D.
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2014-08-22
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试题分析:A项中 ![](https://iknow-pic.cdn.bcebos.com/3801213fb80e7becc1aed1502c2eb9389b506b0f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) ,由正弦定理可求得 ![](https://iknow-pic.cdn.bcebos.com/203fb80e7bec54e7a098c8afba389b504fc26a0f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) ,进而可推断出三角形只有一解; B项中 ![](https://iknow-pic.cdn.bcebos.com/37d12f2eb9389b50d58b32e38635e5dde7116e0f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) 为定值,故可知三角形有一解.C项中由及正弦定理,得 ![](https://iknow-pic.cdn.bcebos.com/d1a20cf431adcbefff39acb7afaf2edda3cc9f76?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) ,所以 ![](https://iknow-pic.cdn.bcebos.com/b8389b504fc2d562197c025ce41190ef76c66c0f?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) .因而B有两值.D项中 ![](https://iknow-pic.cdn.bcebos.com/caef76094b36acafa2ed444d7fd98d1001e99c76?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) ,进而可知 ![](https://iknow-pic.cdn.bcebos.com/4a36acaf2edda3ccf2e96a9102e93901213f9276?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) ,则 ![](https://iknow-pic.cdn.bcebos.com/8c1001e93901213f2b3e9c6d57e736d12f2e9576?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto) 不符合题意,故三角形无解.故选C |
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