N the polygon pictured, what is the measure of angle k°?

.. A solid mechanics model was used for quasi-static loading, excluding second-order time derivatives and mass effect of the composite for an efficient solution. Even though Lagrange displacement field has better accuracy, quadratic serendipity analysis [16] was selected for the model shape functions to control the displacement field of the composite model. This solid mechanics model solves the equations of motion for the composite system and its predefined material properties. ...

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm