The diagonal of a square is 40 m. The area of the square is: Choose the most appropriate option:  A) 600  B) 900  C) 800  D) 500  E) 400

Rationale: arear = 1 / 2 × ( diagonal ) ( power ) 2 = ( 1 / 2 × 40 × 40 ) m ( power ) 2 = 1600 / 2 = 800 m ( power ) 2 answer is c .
Answer: C