Question 535042
If I understand correctly, it should be a 4-pointed star, looking like this:
{{{drawing( 300, 300, -8, 8, -8, 8,
  grid( 5 ),
  green(rectangle( -3, -3, 3, 3 )),
green(triangle( -3, 3, 0, 7, 3, 3 )),
green(triangle( 3, 3, 7, 0, 3, -3 )),
green(triangle( 3, -3, 0, -7, -3, -3 )),green(triangle( -3, -3, -7, 0, -3, 3 ))  
)}}
The area is easy we just add the area of the square plus the area of the four triangles. For the perimeter, we need to calculate the length of the slanted sides of your star.
The area of the square (in square meters) is
{{{6*6=6^2=36}}}
The area of each triangle (in square meters) is
{{{6*4/2=12}}}
The total area (in square meters) is
{{{36+12+12+12+12=84}}}
For the length of the slanted sides, we could use the Pythagoras theorem, or we could just see that if we joined two of those triangles by the 6m side, we would get a square with an area of 24 square meters, meaning that the length we are looking for (the side of our made up square and the slanted side of the star) is  something that squared gives you 24 square meters. In meters, that length is
{{{sqrt(24)=sqrt(4*6)=sqrt(4)*sqrt(6)=2sqrt(6)}}}.
For the perimeter of the star we need to add 8 of those lengths, to get
{{{8*2sqrt(6)=16sqrt(6)}}}