OA and OB are two roads enclosmng an angle of 120°. X and Y start from 'O' at the same time. X travels along OA with a speed of 4 km/h and Y travels along OB with a speed of 3 km/h.The rate at which the shortest distance between X and Y is increasing after 1 h is
37 km/h
13 km/h
A.
Given, speed of x is 4 km/h and y is 3 km/h .
After time t the distance covered by x is 4t and y is 3t.
Let shortest distance between x and y = A.
Then by cosine law
Thus, rate at which shortest distance A changes with tlme is .