A) \[1000\,\pi \]
B) \[5050\,\pi \]
C) \[4950\,\pi \]
D) \[5151\text{ }\pi \]
Correct Answer: B
Solution :
[b] \[\pi [({{r}^{2}}_{2}-{{r}_{1}}^{2})+({{r}_{4}}^{2}-{{r}_{3}}^{2})\] \[+.....+({{r}^{2}}_{100}-{{r}^{2}}_{99})]\] \[\therefore \,\,\,\,\,{{r}_{2}}-{{r}_{1}}={{r}_{4}}-{{r}_{3}}=\] \[={{r}_{100}}-{{r}_{99}}=1\] \[=\pi [{{r}_{1}}+{{r}_{2}}+{{r}_{3}}+{{r}_{4}}+.....+{{r}_{100}}]\] \[=\pi [1+2+3+.....+100]\] \[=5050\pi \,\,sq\,cm\]You need to login to perform this action.
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