Answer:
38cm
Step-by-step explanation:
The perimeter of the quadrilateral
ABCD=AB+BC+DC+AD.
From the question,
AB =9cm, BC=12cm and DC=4cm.
This implies that we need to find the length AD before we can proceed to find the perimeter.
From the diagram, we can find |AD| using Pythagorean Theorem.
[tex] {|AD|}^{2} = {12}^{2} +{5}^{2} [/tex]
[tex]{|AD|}^{2} =144+ 25[/tex]
[tex]{|AD|}^{2} =169[/tex]
Taking positive square root of both sides
[tex]|AD|= \sqrt{169} [/tex]
[tex]|AD|=13 \: cm[/tex]
Hence the perimeter
=9+12+4+13
=38cm
