What is the length of the diagonal of a square with a side that measures 11 centimeters

A square has 4 equal sides

use pythagroeas theorem since a square has 4 right angles

a^2+b^2=c^2

a=b because the sides are equal (11)

11^2+11^2=c^2

242=c^2

square root both sides

11√2=c

the diagonal legnth is 11√2 centimiters