MCQOPTIONS
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| 1. |
If \[{{a}_{1}},\ {{a}_{2}},............,{{a}_{n}}\] are in A.P. with common difference , \[d\], then the sum of the following series is \[\sin d(\cos \text{ec}\,{{a}_{1}}.co\text{sec}\,{{a}_{2}}+\text{cosec}\,{{a}_{2}}.\text{cosec}\,{{a}_{3}}+...........\]\[+\text{cosec}\ {{a}_{n-1}}\text{cosec}\ {{a}_{n}})\] [RPET 2000] |
| A. | \[\sec {{a}_{1}}-\sec {{a}_{n}}\] |
| B. | \[\cot {{a}_{1}}-\cot {{a}_{n}}\] |
| C. | \[\tan {{a}_{1}}-\tan {{a}_{n}}\] |
| D. | \[c\text{osec}\ {{a}_{1}}-\text{cosec}\ {{a}_{n}}\] |
| Answer» C. \[\tan {{a}_{1}}-\tan {{a}_{n}}\] | |