A) \[\frac{3}{2}\sqrt{21}\]
B) \[\frac{2}{3}\sqrt{21}\]
C) \[2\sqrt{21}\]
D) \[7\sqrt{21}\]
Correct Answer: B
Solution :
Length of median BM \[=\frac{1}{2}\sqrt{2(B{{C}^{2}}+B{{A}^{2}})-(A{{C}^{2}})}=\frac{1}{2}\sqrt{2(25+49)-36}\] |
\[=\frac{1}{2}\sqrt{112}=\sqrt{\frac{112}{4}}=\sqrt{28}=2\sqrt{7}\] |
Let\[h\]be height of tower, given\[\tan {{30}^{{}^\circ }}\] \[=\frac{h}{2\sqrt{h}}\Rightarrow h=2\sqrt{\frac{7}{3}}=\sqrt{\frac{28}{3}}.\] |
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