Help find the angle of k please

An arc subtends a central angle measuring 7pi/4 radians what fraction of the circumference is this arc?

Is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis.

Last one and the bottom answer choice is y=(x-4)^2+1 you guys!