Respuesta :

8cm

First we need to look at the side opposite to the missing side

which it is 12cm

now we can see that on the missing side 4cm is right below it

so we do

12cm-4cm

this gives you

8cm

a) 12-4=8

b) 5+4+4+12+9=34

The perimeter is 34cm and the missing length is 8cm.

Or it could be 38 since this unknown length was determined.