The area of the triangle is
(1/2)*(6)*(7) = 21 cm²
The area of the square is
(2)(2) = 4 cm²
The area of the triangle that is not covered by the square is
21 - 4 = 17 cm²
The probability that the dot will be placed outside the square is
17/21
Answer: 17/21 (or 0.81)