To find perimeter, we need the length of all the sides. Note that we are dealing with a regular polygon, so all of its sides are equal.

Statement I gives us one side length. Multiply the side by ten (decagons have ten sides):

Statement II gives us the length of two sides together. Multiply by 5 to get the total perimeter:

Consider pentagon .

I) Side  has the same length as side , 5 inches.

II) Side  is one-third the length of sides ,  and .

What is the perimeter of ? 

To find perimeter, we need to know the length of all the sides.

Statement I gives us the lengths of two sides.

Statement II relates one of the sides given in Statement I to the other three sides:

The answer can be seen more easily by constructing the altitude of  from , as seen below:

Each interior angle of a hexagon measures ,and the altitude also bisects , the vertex angle of isosceles .  is easily proved to be a 30-60-90 triangle, so by the 30-60-90 Triangle Theorem,

The altitude also bisects  at , so

.

Statement 1:  The perimeter is 10.

Given the perimeter of a rectangle is 10, set up the equation such that the sum of twice of length and width are equal to 10.

There are multiple combinations of length and width that will work in this scenario.

Statement 2:  The area is 4.

Write the formula for area of a rectangle and substitute the area.

Statements 1 and 2 require each other in order to solve for the length and width since there are two unknown variables.

Afterward, the Pythagorean Theorem can be used to solve for the diagonal of the rectangle.

Therefore:

If the pentagon is regular, then it is known that each of the internal angles is  degrees, since the sum of the five interior angles of a pentagon is  degrees. Statement 2 does not give new information, nor does it give enough.

Statement 1 does, however. The length of the diagonal can be found by using the law of cosines:

and c is the length of the diagonal.

The relationship between the number of sides of a regular polygon  and the measure of a single angle  is

If we are given that , then we can substitute and solve for   :

making the figure a nine-sided polygon.

Knowing only the measure of each side is neither necessary nor helpful; for example, it is possible to construct an equilateral triangle with sidelength 8 or a square with sidelength 8. 

The correct answer is that Statement 1 alone is sufficient to answer the question, but not Statement 2 alone.

Information about the hexagon is irrelevant, so Statement 2 has no bearing on the answer to the question.

The measures of the exterior angles of any pentagon, one per vertex, total , and they are congruent if the pentagon is regular, so if this is the case, each would measure . But if Statement 1 is true, then an exterior angle of the pentagon measures  . Therefore, Statement 1 is enough to answer the question in the negative.

The sum of the measures of the six interior angles of any hexagon is , so if Statement 1 is true, then the sum of the six numbers is 720, regardless of the individual values. 

Statement 2 is not enough, however, for us to deduce this sum; this only tells us the mean of the third- and fourth-highest values. 

The sum of the measures of the five interior angles of any pentagon is , so if Statement 1 is true, then the sum of the five numbers is 540, regardless of the individual values. 

The mean of five data values multiplied by 5 is the sum of the values, so if Statement 2 is true, then their sum is .

From Statement 1, you can calculate the measure of an interior angle as follows:

From Statement 2, since an interior angle and an exterior angle at the same vertex form a linear pair, they are supplementary, so you can subtract 18 from 180: