Answer with explanation:
Two Adjacent Sides of Rectangle are, a=4 units, and , b=3 units
Diagonal of rectangle

→Diagonal of Rectangle = 5 units, which is the side of Square lying outside the rectangle.
Length of Diagonal of Square

Diagonal of Square formed from rectangle of side 4 cm and 3 cm =5 × 1.414
= 7.070 units
=7.07 units