Basic Geometry : Squares

Study concepts, example questions & explanations for Basic Geometry

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Example Questions

Example Question #61 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 6\sqrt7\).

Possible Answers:

\(\displaystyle 126\sqrt3\)

\(\displaystyle 126\)

\(\displaystyle 252\sqrt2\)

\(\displaystyle 63\sqrt3\)

Correct answer:

\(\displaystyle 126\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(6\sqrt7)^2}{2}=\frac{252}{2}=126\)

 

Example Question #62 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 7\sqrt5\).

Possible Answers:

\(\displaystyle 46\sqrt5\)

\(\displaystyle \frac{245\sqrt2}{4}\)

\(\displaystyle \frac{245}{2}\)

\(\displaystyle 71\sqrt3\)

Correct answer:

\(\displaystyle \frac{245}{2}\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(7\sqrt5)^2}{2}=\frac{245}{2}\)

 

Example Question #63 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 9\sqrt{10}\).

Possible Answers:

\(\displaystyle 405\sqrt2\)

\(\displaystyle 405\)

\(\displaystyle \frac{405}{2}\)

\(\displaystyle 405\sqrt3\)

Correct answer:

\(\displaystyle 405\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(9\sqrt{10})^2}{2}=\frac{810}{2}=405\)

 

Example Question #91 : Squares

Find the area of a square if its diagonal is \(\displaystyle 7\sqrt{10}\).

Possible Answers:

\(\displaystyle \frac{245}{2}\)

\(\displaystyle 245\)

\(\displaystyle 490\sqrt2\)

\(\displaystyle \frac{245\sqrt3}{2}\)

Correct answer:

\(\displaystyle 245\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(7\sqrt{10})^2}{2}=\frac{490}{2}=245\)

 

Example Question #62 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 6\sqrt{10}\).

Possible Answers:

\(\displaystyle 360\sqrt3\)

\(\displaystyle 180\sqrt2\)

\(\displaystyle 180\)

\(\displaystyle 90\sqrt3\)

Correct answer:

\(\displaystyle 180\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(6\sqrt{10})^2}{2}=\frac{360}{2}=180\)

 

Example Question #62 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 8\sqrt{10}\).

Possible Answers:

\(\displaystyle 320\)

\(\displaystyle 320\sqrt3\)

\(\displaystyle 320\sqrt2\)

\(\displaystyle 160\sqrt3\)

Correct answer:

\(\displaystyle 320\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(8\sqrt{10})^2}{2}=\frac{640}{2}=320\)

 

Example Question #67 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 11\sqrt2\).

Possible Answers:

\(\displaystyle \frac{121\sqrt2}{2}\)

\(\displaystyle 121\)

\(\displaystyle \frac{121}{2}\)

\(\displaystyle 121\sqrt3\)

Correct answer:

\(\displaystyle 121\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(11\sqrt{2})^2}{2}=\frac{242}{2}=121\)

 

Example Question #68 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 15\sqrt{10}\).

Possible Answers:

\(\displaystyle 875\)

\(\displaystyle 1125\)

\(\displaystyle 775\)

\(\displaystyle 2250\)

Correct answer:

\(\displaystyle 1125\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(15\sqrt{10})^2}{2}=\frac{2250}{2}=1125\)

 

Example Question #71 : How To Find The Area Of A Square

Find the area of a square if its diagonal is \(\displaystyle 12\sqrt{14}\).

Possible Answers:

\(\displaystyle 1008\)

\(\displaystyle 1008\sqrt2\)

\(\displaystyle 1008\sqrt5\)

\(\displaystyle 504\sqrt{3}\)

Correct answer:

\(\displaystyle 1008\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(12\sqrt{14})^2}{2}=\frac{2016}{2}=1008\)

 

Example Question #751 : Plane Geometry

Find the area of a square if its diagonal is \(\displaystyle \sqrt{30}\).

Possible Answers:

\(\displaystyle 30\sqrt2\)

\(\displaystyle 15\)

\(\displaystyle 30\)

\(\displaystyle 15\sqrt2\)

Correct answer:

\(\displaystyle 15\)

Explanation:

The diagonal of a square is also the hypotenuse of a \(\displaystyle 45-45-90\) triangle.

Picture1

Recall how to find the area of a square:

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

Now, use the Pythagorean theorem to find the area of the square.

\(\displaystyle \text{side}^2+\text{side}^2=\text{Diagonal}^2\)

\(\displaystyle 2(\text{side})^2=\text{Diagonal}^2\)

\(\displaystyle \text{side}^2=\frac{\text{Diagonal}^2}{2}\)

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

Plug in the length of the diagonal to find the area of the square.

\(\displaystyle \text{Area}=\frac{(\sqrt{30})^2}{2}=\frac{30}{2}=15\)

 

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