Since a circle is inscribed in a quadrilateral ABCD, by the property of such a quadrangle, the sums of the lengths of the opposite sides of the quadrilateral are equal.
AD + BC = AB + CD.
By condition, AB + CD = 5 dm, then AD + BC = 5 dm.
The perimeter of the quadrilateral is: Ravsd = (AB + CD) + (AD + BC) = 5 + 5 = 10 dm.
Answer: The perimeter of the quadrangle is 10 dm.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.