A) \[7\,cm\]
B) \[7.5\,cm\]
C) \[8\,cm\]
D) \[4\,cm\]
Correct Answer: B
Solution :
Apply, \[\frac{1}{PA}+\frac{1}{QB}=\frac{1}{RC}\] \[\Rightarrow \,\,\,\,\frac{1}{5}+\frac{1}{QB}=\frac{1}{3}\Rightarrow \frac{1}{5}-\frac{1}{3}=-\frac{1}{QB}\] \[\Rightarrow \,\,\,\,-\frac{2}{15}=-\frac{1}{QB}=\,\Rightarrow QB=\frac{15}{2}\] \[QB=\underline{\mathbf{7}\mathbf{.5}\,\mathbf{cm}}\]You need to login to perform this action.
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