The Top of a Ladder Slides Down a Vertical Wall $0.15 \mathrm {~m} / \mathrm { s }$

Short Answer

The top of a ladder slides down a vertical wall at a rate of $0.15 \mathrm {~m} / \mathrm { s }$ . At the moment when the bottom of the ladder is $1.5 \mathrm {~m}$ from the wall, it slides away from the wall at a rate of $0.3 \mathrm {~m} / \mathrm { s }$ . How long is the ladder?