Pentagons - Math

To find the angle of any regular polygon you find the number of sides . For a pentagon, .

You then subtract 2 from the number of sides yielding 3.

Take 3 and multiply it by 180 degrees to yield the total number of degrees in the regular pentagon.

Then to find one individual angle we divide 540 by the total number of angles 5,

The answer is .

The following equation can be used to determine the measure of an interior angle of a regular polygon, where equals the number of sides.

In a pentagon, .

Now we can solve for the angle.

The formula for the sum of the interior angles of a polygon is

,

where is the number of sides in the polygon

Plugging in our values, we get:

Dividing the sum of the interior angles by the number of angles in the polygon, we get the value for each interior angle:

The measure of an interior angle of a regular polygon can be determined using the following equation, where equals the number of sides:

The sum of the angles in a polygon is

For a pentagon, this equals 540. Since the first 3 angles add up to 240, the remaining 2 angles must add up to

The perimeter in this question is irrelevant. Use the interior angle formula to determine the total sum of the angles in a hexagon.

There are six interior angles in a hexagon.

Each angle will be a sixth of the total angle.

Therefore, the sum of three angles in a hexagon is:

Use the interior angle formula to find the total sum of angles in a pentagon.

for a pentagon, so substitute this value into the equation and solve:

Divide this number by 5, since there are five interior angles.

The sum of four interior angles in a regular pentagon is:

The perimeter of a regular pentagon has no effect on the interior angles of the pentagon.

Use the following formula to solve for the sum of all interior angles in the pentagon.

Since there are 5 sides in a pentagon, substitute the side length .

Divide this by 5 to determine the value of each angle, and then multiply by 2 to determine the sum of 2 interior angles.

The sum of 2 interior angles of a pentagon is .

Area has no effect on the value of the interior angles of a pentagon. To find the sum of all angles of a pentagon, use the following formula, where is the number of sides:

There are 5 sides in a pentagon.

Divide this number by 5 to determine the value of each angle.

The pentagon has 5 sides. To find the value of the interior angle of a pentagon, use the following formula to find the sum of all interior angles.

Substitute .

Divide this number by 5 to determine the value of each interior angle.

Every interior angle is 108 degrees. The problem states that an interior angle is . Set these two values equal to each other and solve for .

A regular polygon with sides has congruent angles, each of which measures

Setting , the common angle measure can be calculated to be

The statement is therefore false.

If one exterior angle is taken at each vertex of any polygon, and their measures are added, the sum is . Each exterior angle of a regular pentagon has the same measure, so if we let be that common measure, then

Solve for :

The statement is true.

Suppose Pentagon is regular. Each angle of a regular polygon of sides has measure

A pentagon has 5 sides, so set ; each angle of the regular hexagon has measure

Since one angle is given to be of measure , the pentagon might be regular - but without knowing more, it cannot be determined for certain. Therefore, the correct choice is "undetermined".

To find the side length of a regular pentagon with a perimeter of you must use the equation for the perimeter of a pentagon.

The equation is

Plug in the numbers for perimeter and number of sides to get

Divide each side of the equation by the number of sides to get the answer for the side length.

The answer is .

The formula for the perimeter of a regular pentagon is

,

where represents the length of the side.

Plugging in our values, we get:

The formula for the perimeter of a regular pentagon is

,

where represents the length of the side.

Plugging in our values, we get:

Use the Pythagorean Theorem to find the length of the diagonal:

Use the Pythagorean Theorem to find the length of the diagonal:

From the given information, we can imagine the following image

In order to solve for the perimeter, we need to solve for the length of one of the sides. This can be accomplished by creating a right triangle from the apothem and the top angle that's marked.

This angle measure can be calculated through:

, where the sum of all the angles around the center of the pentagon sum up to and the is for the number of sides. We can do this because all of the interior angles of the pentagon will be equal because it is regular. Then, this answer needs to be divided by because the pictured right triangle is half of a larger isosceles triangle.

Therefore, the marked angle is .

Now that one side and one angle are known, we can use SOH CAH TOA because this is a right triangle. In this case, the tangent function will be used because the mystery side of interest is opposite of the known angle, and we are already given the adjacent side (the apothem). In solving for the unknown side, we will label it as .

For a more precise answer, keep the entire number in your calculator. This will prevent rounding errors.

Keep in mind that the base of the triangle is actually only half the length of the side. This means that the value for must be multiplied by .

In order to solve for the perimeter, the length of the side needs to be multiplied by the number of sides; in this case, there are five sides.

This is the final answer, so the entire decimal is no longer needed. Rounded, the perimeter is .

Write the formula to find the perimeter of a pentagon.

Substitute the side length into the equation and simplify.