What is the sum of the geometric series e (-)^n-1

Adozen bananas weigh 3 pounds how many ounces does 1 banana weigh

Can someone me with this problem i don't understand i need

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?