Question 547967
The length of the longer side is {{{2*6=12}}}
In a rectangle, the sides that are parallel to each other have the same length. so, your rectangle, with the sides' length is cm, looks like this.
{{{drawing(300, 150, -2, 14, -1,7,
rectangle(0,0,12,6),
locate(-0.5,3.5,6),locate(12.2,3.5,6),
locate(5.5,0,12),locate(5.5,6.8,12)
)}}}The perimeter of a figure is the length all around that figure. You find it by adding the length of all sides. When you know the length of all the sides, That's easy to do.
{{{Perimeter=6+12+6+12=36}}}
The perimeter of your rectangle is 36 cm.
Rectangles are easier than other figures, because the two long sides have the same measure (usually called the length), and the two short sides have the same measure (usually called the width).
You may have been given formulas (recipes) to calculate the perimeter of a rectangle, like
Perimeter = 2Xlength + 2Xwidth or
Perimeter = 2X(length+width)