What is the perimeter of a circle whose area is 11

What is the smallest integer n such that n\sqrt{2} is greater than 20

Parabolas y=−2x^2 and y=2x^2 +k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.

Acyclist bike x distance at 10 miles per hour .and returns over the same path at 8 miles per hour.what is the cyclist average rate for the round trip in miles per hour ?