Prove that an isosceles trapezium is always cyclic

The actual width ( w) of a regulation soccer field is 90 meters (m), and the actual length is 120 meters (m). a coach has drawn a scale model of the field on a blackboard. if the longest side of his drawing is 18 cm, how long is the other side of the drawing( w)?

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

Sally deposited money into a savings account paying 4% simple interest per year. the first year, she earned $75 in interest. how much interest will she earn during the following year?