What is the answer to this question

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?

Which radical expression is a rational number? a. √ 360 b. √ 644 c. √ 225 d. √ 122

How many degrees are there in the central angles in a circle