PSAT Math : Hexagons

Study concepts, example questions & explanations for PSAT Math

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Example Questions

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Example Question #1 : How To Find An Angle In A Hexagon

If a triangle has 180 degrees, what is the sum of the interior angles of a regular octagon?

Possible Answers:

Correct answer:

Explanation:

The sum of the interior angles of a polygon is given by  where  = number of sides of the polygon.  An octagon has 8 sides, so the formula becomes

Example Question #1 : How To Find An Angle In A Hexagon

In a rectangular hexagon, what is the meaure of each interior angle?

Possible Answers:

150 degrees

90 degrees

72 degrees

120 degrees

105 degrees

Correct answer:

120 degrees

Explanation:

The sum of the interior angles of a hexagon must equal 720 degrees. Because the hexagon is regular, all of the interior angles will have the same measure. A hexagon has six sides and six interior angles. Therefore, each angle measures.

Example Question #1 : How To Find An Angle In A Hexagon

Hexagon

Note:Figure NOT drawn to scale.

Refer to the above figure. Evaluate .

Possible Answers:

Correct answer:

Explanation:

The sum of the degree measures of the angles of a (six-sided) hexagon, is

We can solve for  in the equation

Example Question #5 : How To Find An Angle In A Hexagon

Hexagon

Note: Figure NOT drawn to scale.

Refer to the above figure. Evaluate .

Possible Answers:

Correct answer:

Explanation:

The sum of the degree measures of the angles of a (six-sided) hexagon, is

We can solve for  in the equation

 

Example Question #1 : How To Find An Angle In A Hexagon

Three angles of a hexagon measure . The other three angles are congruent to one another. What is the measure of each of the latter three angles?

Possible Answers:

This hexagon cannot exist.

Correct answer:

Explanation:

The sum of the degree measures of the angles of a (six-sided) hexagon, is

Let  be the common measure of the three congruent angles in question. We can solve for  in the equation

Example Question #7 : How To Find An Angle In A Hexagon

What is the measurement of one of the interior angles of a regular hexagon?

Possible Answers:

Correct answer:

Explanation:

To find the sum of the interior angles of any regular polygon, use the formula , where  represents the number of sides of the regular polygon.

The sum of the interior angles of a regular hexagon is 720 degrees. To find the measurement of one angle, divide by the number of interior angles (or sides):

The measurement of one angle in a regular hexagon is 120 degrees.

Example Question #1 : How To Find The Area Of A Hexagon

Calculate the approximate area a regular hexagon with the following side length:

Possible Answers:

Cannot be determined 

Correct answer:

Explanation:

How do you find the area of a hexagon?

There are several ways to find the area of a hexagon.

  1. In a regular hexagon, split the figure into triangles.
  2. Find the area of one triangle.
  3. Multiply this value by six.

Alternatively, the area can be found by calculating one-half of the side length times the apothem.

 

Regular hexagons:

Regular hexagons are interesting polygons. Hexagons are six sided figures and possess the following shape:

In a regular hexagon, all sides equal the same length and all interior angles have the same measure; therefore, we can write the following expression.

 

One of the easiest methods that can be used to find the area of a polygon is to split the figure into triangles. Let's start by splitting the hexagon into six triangles. 

Screen shot 2016 07 06 at 2.09.44 pm

In this figure, the center point, , is equidistant from all of the vertices. As a result, the six dotted lines within the hexagon are the same length. Likewise, all of the triangles within the hexagon are congruent by the side-side-side rule: each of the triangle's share two sides inside the hexagon as well as a base side that makes up the perimeter of the hexagon. In a similar fashion, each of the triangles have the same angles. There are  in a circle and the hexagon in our image has separated it into six equal parts; therefore, we can write the following:

Screen shot 2016 07 06 at 2.27.41 pm

We also know the following:

Now, let's look at each of the triangles in the hexagon. We know that each triangle has two two sides that are equal; therefore, each of the base angles of each triangle must be the same. We know that a triangle has  and we can solve for the two base angles of each triangle using this information.

Each angle in the triangle equals . We now know that all the triangles are congruent and equilateral: each triangle has three equal side lengths and three equal angles. Now, we can use this vital information to solve for the hexagon's area. If we find the area of one of the triangles, then we can multiply it by six in order to calculate the area of the entire figure. Let's start by analyzing . If we draw, an altitude through the triangle, then we find that we create two  triangles. 

Screen shot 2016 07 06 at 2.27.10 pm

Let's solve for the length of this triangle. Remember that in  triangles, triangles possess side lengths in the following ratio:

Now, we can analyze  using the a substitute variable for side length, .

Screen shot 2016 07 06 at 3.01.03 pm

We know the measure of both the base and height of  and we can solve for its area.

Now, we need to multiply this by six in order to find the area of the entire hexagon.

We have solved for the area of a regular hexagon with side length, . If we know the side length of a regular hexagon, then we can solve for the area.

If we are not given a regular hexagon, then we an solve for the area of the hexagon by using the side length(i.e. ) and apothem (i.e. ), which is the length of a line drawn from the center of the polygon to the right angle of any side. This is denoted by the variable  in the following figure:

Screen shot 2016 07 06 at 3.17.05 pm

 

Alternative method:

If we are given the variables  and , then we can solve for the area of the hexagon through the following formula:

In this equation,  is the area,  is the perimeter, and  is the apothem. We must calculate the perimeter using the side length and the equation , where  is the side length.

 

Solution:

In the given problem we know that the side length of a regular hexagon is the following:

Let's substitute this value into the area formula for a regular hexagon and solve.

Simplify.

Round the answer to the nearest whole number.

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