In a ABC, if cot(A) cot(B) cot(C) > 0, then the triangle is
acute angled
right angled
obtuse angled
does not exist
A man 2 m tall walks at a uniform speed of 5 km/h away from a lamp post 6 m high. The rate at which the length of his shadow increases, is
2.5km/h
5km/h
15km/h
A.
2.5km/h
Let the person reaches F from the lamp post A and let his shadow is BF.