In this right triangle
Applying the Pythagorean Theorem
C^2=A^2+B^2
where
C^2------> area of square C
A^2 -----> area of square A
B^2 ----> area of square B
substitute the given values
42=15+B^2
solve for B^2
B^2=42-15
B^2=27
therefore
the area of square B is 27 square centimeters
