What value of theta is cos ^-1(sqrt2/2)=theta

Jack lives on a farm and has a large backyard. the area of his rectangular backyard is of a square mile. if the width of the yard is of a mile, what fraction of a mile is the length of the rectangular backyard?

Abcd is reflected across the x- axis, then rotated 90 clockwise about the orgin, and finally reflected across the line y= x to form a’ b’ c’ .

Which term describes the point where the perpendicular bisectors of the three sides of a triangle intersect?