A man is moving away from a tower high at a rate of

MATHEMATICS · Single correct · A Level · Mathematics · Differentiation · Differentiation

Problem

A man is moving away from a tower

41.6\,\text{m}

high at a rate of

2\,\text{m/s}

. If the eye level of the man is

1.6\,\text{m}

above the ground, then the rate at which the angle of elevation of the top of the tower changes, when he is at a distance of

30\,\text{m}

from the foot of the tower, is (a)

-\frac{4}{125}\,\text{rad/s}

(b)

-\frac{2}{25}\,\text{rad/s}

(c)

-\frac{1}{625}\,\text{rad/s}

(d) none of these