A) 2 cm
B) 2/5 cm
C) 4 cm
D) 4/5 cm
Correct Answer: B
Solution :
\[\frac{Area\,of\,\Delta \,ADE}{Area\,of\,\Delta \,ABC}=\frac{D{{E}^{2}}}{B{{C}^{2}}}\] or \[\frac{\frac{1}{5}\times Area\,of\,\Delta \,ABC}{Area\,of\,\Delta \,ABC}=\frac{D{{E}^{2}}}{{{10}^{2}}}\] or \[\frac{1}{5}=\frac{D{{E}^{2}}}{100}\] or \[D{{E}^{2}}=\frac{100}{5}=20\] \[\therefore \] \[DE=\sqrt{20}\] \[=2\sqrt{5}\,CM\]You need to login to perform this action.
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