A 10-foot ladder leans against the side of a building as in example 7.2. If the bottom of the ladder is pulled away from the wall at the rate of 3 ft/s and the ladder remains in contact with the wall, (a) find the rate at which the top of the ladder is dropping when the bottom is 6 feet from the wall.
(b) Find the rate at which the angle between the ladder and the horizontal is changing when the bottom of the ladder is 6 feet from the wall.
1
Expert's answer
2021-10-12T04:24:40-0400
By pythagoras theorem 102=x2+y2Differentiating, we have 2xdtdx+2ydtdy=0⟹dtdy=−yxdtdxwhere y=102−62=8∴dtdy=−86⋅3=−4−9tanθ(t)=yxDifferentiating, we have sec2θ(t)θ′(t)=y2y(t)x′(t)−x(t)y′(t)sec2θ(t)θ′(t)=828⋅3−6⋅−49=0.586=θ′(t)=0.586cos2(36.87)=0.375
Comments
Leave a comment