If line segment ab represents 25% what is the length of a line segment that is 100%

Sketch one cycle if the cosine function y=2cos2theta

If 25% of y is 30, what is 60% of y?

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?