$2\mathrm{.}3\mathrm{.}19.[$Level $2]$ A light, rigid pole with a heavy lumped

mass on its end is being hoisted up with a constant angular

speed of $=0\mathrm{.}25ra\frac{d}{s}$ by means of a rope being reeled into

a spool to the left of the pole's base. The rope is attached

to the lumped mass on the pole's end, and let $r$ describe the

length of rope from the spool to the lumped mass. At a cer.

tain instant the rope makes an angle of $40$ with the ground,

and the pole is vertical. If the pole is $20$ ft long, find what $r,$

$r^{},r^{},{}^{},$ and ${}^{}$ are at this instant.