Place parenthesis and x; /; +; or - between some of the digits to make this equation true:
9 9 9 9=1

Answer the questions in the attachment. a rescue helicopter is at point a and a rescue boat is at point e. the helicopter pilot spots boats in distress at points d and c, with angles as marked in the diagram. figure abce is a rectangle. the altitude of the rescue helicopter, represented by ae, is 5000 feet.

Thales was an ancient philosopher familiar with similar triangles. one story about him says that he found the height of a pyramid by measuring its shadow and his own shadow at the same time. if the person is 5-ft tall, what is the height of the pyramid in the drawing?

How is working backward similar to solving an equation?