question_answer

A ladder is resting with the wall at an angle of \[{{30}^{o}}\]. A man is ascending the ladder at the rate of 3 ft/sec. His rate of approaching the wall is

A)            3 ft/sec

B)            \[\frac{3}{2}\]ft/sec

C)  \[\frac{3}{4}\]ft/sec

D)  \[\frac{3}{\sqrt{2}}\]ft/sec

Correct Answer: B

Solution :

                     His rate of approaching the wall \[=3\times \cos 60{}^\circ =\frac{3}{2}ft/sec\].