To find the perimeter of a polygon, simply add the sides.
Here, the sides are: a, a+1, a+2, and 3(a+3)
So,
[tex]a+(a+1)+(a+2)+3(a+3)[/tex]
Now, do the distributive property and combine like terms,[tex]a+a+1+a+2+3a+9[/tex][tex]6a+12[/tex]
The answer is 6a + 12. Hope this helps and have a terrific day!
