Intermediate Geometry : Intermediate Geometry

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #2 : How To Find The Area Of A Hexagon

 

 

A regular (also known as equilateral) hexagon has an apothem length of  \(\displaystyle 7\sqrt{3}\).

Find the area of the hexagon.

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Possible Answers:

\(\displaystyle 154\sqrt{6}\)

\(\displaystyle 147\sqrt{3}\)

\(\displaystyle 208\sqrt{6}\)

None of the other answers

\(\displaystyle 294\sqrt{3}\)

Correct answer:

\(\displaystyle 294\sqrt{3}\)

Explanation:

Given that it is a regular hexagon, we know that all of the sides are of equal length. Therefore, all 6 of the triangles (we get from drawing lines to opposite vertexes) are congruent triangles.

Lets use the fact that there are 360 degrees in a full rotation. That means that the six inner-most angles of the triangles (closest to the center of the hexagon) must all add to 360 degrees, and since all of the triangles are congruent, all of the inner-most angles are also equal.

\(\displaystyle \frac{360}{6}=60^{\circ}\)

 

If the innermost angle is 60 degrees, and the fact that it is a regular hexagon, we can therefore state that the other two angles are

\(\displaystyle \frac{\left ( 180-60 \right )}{2}=60^{\circ}\) 

as well. Since all of the angles are 60 degrees, it is an equilateral triangle.

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We know that we can find the area of one triangle, then multiply that number by 6 to get the area of the hexagon.

 

With that in mind, we look at the right triangle.

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Look familiar?? The 30-60-90 and 45-45-90 right triangles appear often, so it's worth it to remember the shortcuts to the Pythagorean Theorem so you don't have to do the calculations every time.

 

For our numbers we have  \(\displaystyle \mathbf{a}\sqrt{3} = 7\sqrt{3}}\), so our base is going to be 7 cm.

The base of the larger equilateral triangle is going to be twice as big, so

\(\displaystyle 7\cdot 2=14\ cm\).

Plug these into

\(\displaystyle A=base\cdot height\cdot \frac{1}{2}\)

and then multiply by 6 (remember we want the area of all 6 triangles inside of the hexagon)

\(\displaystyle 14 \cdot 7\sqrt{3} \cdot \frac{1}{2} = 49\sqrt{3}}\)

\(\displaystyle 49\sqrt{3} \cdot 6 = 294\sqrt{3}\approx 509.22\)

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

Find the area of a regular hexagon with a side length of \(\displaystyle 4\).

Possible Answers:

\(\displaystyle 36\sqrt3\)

\(\displaystyle 8\sqrt3\)

\(\displaystyle 48\sqrt3\)

\(\displaystyle 24\sqrt3\)

Correct answer:

\(\displaystyle 24\sqrt3\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(4^2)=\frac{3\sqrt3}{2}(16)=\frac{48\sqrt3}{2}=24\sqrt3\)

Example Question #2 : How To Find The Area Of A Hexagon

Find the area of a regular hexagon with a side length of \(\displaystyle 5\).

Possible Answers:

\(\displaystyle 25\sqrt3\)

\(\displaystyle \frac{75\sqrt3}{2}\)

\(\displaystyle \frac{5\sqrt3}{2}\)

\(\displaystyle 5\sqrt3\)

Correct answer:

\(\displaystyle \frac{75\sqrt3}{2}\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(5^2)=\frac{3\sqrt3}{2}(25)=\frac{75\sqrt3}{2}\)

Example Question #3 : How To Find The Area Of A Hexagon

Find the area of a regular hexagon with a side length of \(\displaystyle 2\).

Possible Answers:

\(\displaystyle 6\sqrt3\)

\(\displaystyle 10\sqrt3\)

\(\displaystyle 12\sqrt3\)

\(\displaystyle 4\sqrt3\)

Correct answer:

\(\displaystyle 6\sqrt3\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(2^2)=\frac{3\sqrt3}{2}(4)=\frac{12\sqrt3}{2}=6\sqrt3\)

Example Question #4 : How To Find The Area Of A Hexagon

Find the area of a regular hexagon with a side length of \(\displaystyle 6\).

Possible Answers:

\(\displaystyle 95\sqrt3\)

\(\displaystyle 54\sqrt3\)

\(\displaystyle 108\sqrt3\)

\(\displaystyle 64\sqrt3\)

Correct answer:

\(\displaystyle 54\sqrt3\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(6^2)=\frac{3\sqrt3}{2}(36)=\frac{108\sqrt3}{2}=54\sqrt3\)

Example Question #101 : Hexagons

Find the area of a regular hexagon with a side length of \(\displaystyle 10\).

Possible Answers:

\(\displaystyle 300\sqrt3\)

\(\displaystyle 250\sqrt3\)

\(\displaystyle 200\sqrt3\)

\(\displaystyle 150\sqrt3\)

Correct answer:

\(\displaystyle 150\sqrt3\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(10^2)=\frac{3\sqrt3}{2}(100)=\frac{300\sqrt3}{2}=150\sqrt3\)

Example Question #102 : Hexagons

Find the area of a regular hexagon with side lengths of \(\displaystyle 7\).

Possible Answers:

\(\displaystyle 147\sqrt3\)

\(\displaystyle \frac{49\sqrt3}{2}\)

\(\displaystyle \frac{147\sqrt3}{2}\)

\(\displaystyle 49\sqrt3\)

Correct answer:

\(\displaystyle \frac{147\sqrt3}{2}\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(7^2)=\frac{3\sqrt3}{2}(49)=\frac{147\sqrt3}{2}\)

Example Question #911 : Intermediate Geometry

In terms of \(\displaystyle x\), find the area of a regular hexagon with side lengths of \(\displaystyle 2x\).

Possible Answers:

\(\displaystyle 9x^2\sqrt3\)

\(\displaystyle 12x^2\sqrt3\)

\(\displaystyle 6x\sqrt3\)

\(\displaystyle 6x^2\sqrt3\)

Correct answer:

\(\displaystyle 6x^2\sqrt3\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(2x)^2=\frac{3\sqrt3}{2}(4x^2)=\frac{12x^2\sqrt3}{2}=6x^2\sqrt3\)

Example Question #912 : Intermediate Geometry

In terms of \(\displaystyle x\), find the area of a regular hexagon with side lengths \(\displaystyle 12x\).

Possible Answers:

\(\displaystyle 288x^2\sqrt3\)

\(\displaystyle 216x\sqrt3\)

\(\displaystyle 432x^2\sqrt3\)

\(\displaystyle 216x^2\sqrt3\)

Correct answer:

\(\displaystyle 216x^2\sqrt3\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(12x)^2=\frac{3\sqrt3}{2}(144x^2)=\frac{432x^2\sqrt3}{2}=216x^2\sqrt3\)

Example Question #913 : Intermediate Geometry

In terms of \(\displaystyle x\), find the area of a regular hexagon with side lengths \(\displaystyle 9x\).

Possible Answers:

\(\displaystyle \frac{143x^2\sqrt3}{2}\)

\(\displaystyle \frac{243x^2\sqrt3}{2}\)

\(\displaystyle \frac{81x^2\sqrt3}{2}\)

\(\displaystyle 243x^2\sqrt3\)

Correct answer:

\(\displaystyle \frac{243x^2\sqrt3}{2}\)

Explanation:

Use the following formula to find the area of a regular hexagon:

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}side^2\)

Now, substitute in the value for the side length.

\(\displaystyle \text{Area}=\frac{3\sqrt3}{2}(9x)^2=\frac{3\sqrt3}{2}(81x^2)=\frac{243x^2\sqrt3}{2}\)

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