## Elementary Geometry for College Students (6th Edition)

a=5 r=5$\sqrt 2$
2a=s 2a=10 a=5 The radius, apothem, and half of a side of a square form a 45 45 90 triangle. Therefore, the radius is equal to the apothem times the square root of 2. r=a$\sqrt 2$ r=5$\sqrt 2$