1. In the trapezoid ABCD, AD / / BC, ab = ad = DC = 2cm, angle c = 45 ° to find the perimeter of the trapezoid

Vertical BC of de through D
Because the angle c is 45 degrees
So CE = De
According to Pythagorean relationship, EC square + ed square = DC square
Get CE = root two
AF ⊥ BC through a
Similarly, BF = radical two
Perimeter = AD + DC + AB + BC = AD + DC + AB + BF + Fe + EC = 8 + double root 2

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