The sum of the interior angles of a polygon is equal to 180 degrees multiplied by the number of sides minus 2. This can be written as the formula:
Sum of Interior Angles = (n - 2) * 180 degrees
where n is the number of sides of the polygon.
If the sum of the interior angles of a polygon is 1980 degrees, we can solve for the number of sides by setting up the equation:
1980 degrees = (n - 2) * 180 degrees
Then, we can solve for n by dividing both sides of the equation by 180 degrees:
1980 degrees / 180 degrees = (n - 2) * 180 degrees / 180 degrees
This simplifies to:
11 = n - 2
Then, we can solve for n by adding 2 to both sides of the equation:
11 + 2 = n
This gives us:
n = 13
Therefore, the polygon has 13 sides.