In order to do this you would have to use the Pythagorean Theorem which is a^2 +b^2 =c^2. Because we know that the top line is equal to 5 inches then you can assume that the line from the line that equals 3 inches to the left bottom left corner of the trapezoid equals 2 inches because this trapezoid is signifying that both sides are equal. So then you would use the Pythagorean Theorem to find the two unknown sides by doing 2^2 +3^2=c^2 when you combine like terms, it comes out to be 13=c^2 which when you square root it, equals about 3.6. So then you know that each of the unknown sides equal 3.6, so then you add them all up to get 3.6+5+3.6+9=21.2 inches Hope this helps