Step 1: Apply the Pythagorean theorem The diagonal \( d \) of a rectangle is calculated using the Pythagorean theorem, where it forms a right triangle with the rectangle's length and breadth as its perpendicular sides. The theorem is expressed as:\[d^2 = l^2 + b^2\]Here, \( l \) represents the length, \( b \) the breadth, and \( d \) the diagonal.Step 2: Input the provided measurements Given:- \( l = 6 \, \text{cm} \),- \( b = 8 \, \text{cm} \).Insert these values into the formula:\[d^2 = 6^2 + 8^2 = 36 + 64 = 100\]\[d = \sqrt{100} = 10 \, \text{cm}\]Answer: The diagonal measures \( 10 \, \text{cm} \). This corresponds to option (1).