A 18 ft ladder leans against a wall. The bottom of the ladder is 4 ft from the wall at time t=0 and slides away from the wall at a rate of 3ft/sec.

Find the velocity of the top of the ladder at time t=1.

The velocity of ladder at time t=1 is __________ ft/sec.

1 answer

look at the triangle.

c^2=b^2+h^2 b= base, h=height

take derivitave
d c^2/dt=0=2bdb/dt + 2h dh/dt

b=4, db/dt=3ft/sec h=sqrt(18^2-4^2)

find dh/dt