A) 36 km/hr
B) 72 km/hr
C) 18 km/hr
D) 30 km/hr
Correct Answer: A
Solution :
\[CD=h\text{ }(\cot {{30}^{o}}-\cot {{45}^{o}})\] \[15\,(\sqrt{3}+1)\,[\cot {{30}^{o}}-\cot {{45}^{o}}]\] \[=15\,(\sqrt{3}+1)\,(\sqrt{3}-1)\] = \[15\,(3-1)=30m\] Speed = \[\frac{30}{1000}\times \frac{60\times 60}{3}km/hr\]= \[36km/hr\].You need to login to perform this action.
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