A) 6 cm
B) 12 cm
C) 18 cm
D) 24 cm
Correct Answer: D
Solution :
\[f=\frac{({{D}^{2}}-{{x}^{2}})}{4D}\] Here, \[D=100\,\,cm,\] and \[x=20\,\,cm\] \[\therefore \] \[f=\frac{[{{(100)}^{2}}-{{(20)}^{2}}}{4\times 100}\] \[=\frac{10000-400}{400}\] \[\mathbf{=24}\,\,\mathbf{cm}\]You need to login to perform this action.
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