What measuring tool and unit you would use to measure a rectangle explain

Raj encoded a secret phrase using matrix multiplication. using a = 1, b = 2, c = 3, and so on, he multiplied the clear text code for each letter by the matrix to get a matrix that represents the encoded text. the matrix representing the encoded text is . what is the secret phrase? determine the location of spaces after you decode the text. yummy is the corn the tomato is red the corn is yummy red is the tomato

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)

Which rotation about its center will carry a regular hexagon onto itself