13. Ann and Kelly are standing on a river bank, wondering how wide the river is. Ann is wearing
a baseball cap, so she comes up with the follow-
ing idea: She lowers her cap until she sees the tip
of the visor just at the opposite bank of the river.
She then turns around 180°, to face away from
the river, being careful not to tilt her head or cap,
and has Kelly walk to the spot where she can just
see Kelly's shoes. By pacing off the distance be-
tween them, Ann and Kelly figure that Kelly was
50 feet away from Ann. If the ground around
the river is level, what, if anything, can Ann and
Kelly conclude about how wide the river is? Re-
late this to triangle congruence,