Basic Geometry : Triangles

Study concepts, example questions & explanations for Basic Geometry

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Example Questions

Example Question #121 : Right Triangles

A right triangle has one side measuring \(\displaystyle 3in\), and one side measuring \(\displaystyle 5in\). The last and missing side is the hypotenuse. Find the length of the hypotenuse in inches. 

Possible Answers:

\(\displaystyle 5in\)

\(\displaystyle 4.7in\)

\(\displaystyle 6.2in\)

\(\displaystyle 5.8in\)

\(\displaystyle 10in\)

Correct answer:

\(\displaystyle 5.8in\)

Explanation:

By using the Pythagorean Theorem \(\displaystyle a^2+b^2=c^2\), you find the correct answer of \(\displaystyle 5.8in\)

This is done by plugging in \(\displaystyle 3=a\), and \(\displaystyle 5=b\), since \(\displaystyle c\) was described as the hypotenuse. This gives us:

\(\displaystyle 3^2 + 5^2 = c^2\)

\(\displaystyle 9 + 25 = c^2\)

\(\displaystyle 34 = c^2\)

\(\displaystyle \sqrt{}34 = c\)

\(\displaystyle 5.8=c\)

Example Question #1301 : Basic Geometry

Find the hypotenuse of a triangle whose side lengths are 10 and 3.

Possible Answers:

\(\displaystyle \sqrt{26}\)

\(\displaystyle \sqrt{109}\)

\(\displaystyle \sqrt{13}\)

\(\displaystyle \sqrt{103}\)

Correct answer:

\(\displaystyle \sqrt{109}\)

Explanation:

To solve, simply use the Pythagorean Theorem.

The hypotenuse is the c value in the equation and the two smaller leg lengths are a and b.

Let,

\(\displaystyle \\a=10 \\b=3\)

thus,

\(\displaystyle \\c=\sqrt{a^2+b^2}\\c=\sqrt{10^2+3^2}\\c=\sqrt{100+9}\\c=\sqrt{109}\).

Example Question #1302 : Basic Geometry

Find the hypotenuse of a right triangle with width and length 3 and 5 respectively.

Possible Answers:

\(\displaystyle 8\)

\(\displaystyle 4\)

\(\displaystyle \sqrt{34}\)

\(\displaystyle \sqrt{15}\)

Correct answer:

\(\displaystyle \sqrt{34}\)

Explanation:

To find the diagonal of a rectangle recall that the diagonal will create a triangle where the width and length are legs of the triangle and the diagonal is the hypotenuse.

To solve, simple use the Pythagorean Theorem and solve for the hypotenuse, which will be the diagonal of the rectangle.

Thus,

\(\displaystyle c=\sqrt{a^2+b^2}=\sqrt{3^2+5^2}=\sqrt{9+25}=\sqrt{34}\)

Example Question #89 : How To Find The Length Of The Hypotenuse Of A Right Triangle : Pythagorean Theorem

The two shortest sides of a right triangle are each \(\displaystyle 10 cm\). What is the length of the hypotenuse?

Possible Answers:

\(\displaystyle 2\sqrt{10}cm\)

\(\displaystyle 10\sqrt{2}cm\)

\(\displaystyle 200cm\)

\(\displaystyle 100cm\)

\(\displaystyle 10cm\)

Correct answer:

\(\displaystyle 10\sqrt{2}cm\)

Explanation:

The Pythagorean Theorem states that:

\(\displaystyle a^2+b^2=c^2\)

Because we know that \(\displaystyle a\) and \(\displaystyle b\) are both \(\displaystyle 10 cm\), we can plug those in to find \(\displaystyle c\):

\(\displaystyle 10^2+10^2=c^2\)

\(\displaystyle 100+100=c^2\)

\(\displaystyle 200=c^2\)

\(\displaystyle c=\sqrt{200}=\sqrt{100}\times \sqrt{2} = 10\sqrt{2}\)

Therefore, the triangle's hypotenuse is \(\displaystyle 10\sqrt{2}cm\).

Example Question #90 : How To Find The Length Of The Hypotenuse Of A Right Triangle : Pythagorean Theorem

Find the length of the hypotenuse using Pythagorean Theorem.

The triangle has two other sides with lengths 3 and 4 inches.

Possible Answers:

\(\displaystyle 25\ inches\)

\(\displaystyle 50\ inches\)

\(\displaystyle 5\ inches\)

\(\displaystyle 12\ inches\)

\(\displaystyle 10\ inches\)

Correct answer:

\(\displaystyle 5\ inches\)

Explanation:

The formula for Pythagorean Theorem is, \(\displaystyle A^2 + B^2 = C^2\)

C is the hypotenuse and A and B are the other two sides. To begin Pythagorean Theorem the order of A and B does not matter.

If A is 3 and B is 4 then,

\(\displaystyle 3^2 + 4^2 = C^2\)

\(\displaystyle 9 + 16 = C^2\)

\(\displaystyle 25 = C^2\)

You must find C and not c squared. Therefore to get rid of the squared you must do the opposite of squaring something, which is the square root of something. 

\(\displaystyle \sqrt{25} = \sqrt{C^2}\)

\(\displaystyle 5 = C\)

5 inches

Example Question #323 : Triangles

Find the length of the hypotenuse of the following right triangle.

9

Possible Answers:

\(\displaystyle 4\sqrt5\)

\(\displaystyle \sqrt{29}\)

\(\displaystyle 2\sqrt{29}\)

\(\displaystyle 3\sqrt{21}\)

Correct answer:

\(\displaystyle 2\sqrt{29}\)

Explanation:

Recall the Pythagorean Theorem, which is used to find the length of the hypotenuse.

For any triangle with leg lengths of \(\displaystyle a\) and \(\displaystyle b\),

13

\(\displaystyle \text{Hypotenuse}^2=a^2+b^2\)

Take the square root of both sides to find the length of the hypotenuse.

\(\displaystyle \text{Hypotenuse}=\sqrt{a^2+b^2}\)

Plug in the given values to find the length of the hypotenuse.

\(\displaystyle \text{Hypotenuse}=\sqrt{10^2 + 4^2}=\sqrt{116}\)

Simply:

\(\displaystyle \sqrt{4}\cdot\sqrt{29}\)

\(\displaystyle 2\sqrt{29}\)

Example Question #1303 : Basic Geometry

Justin travels \(\displaystyle 15\textup{ feet}\) to the east and \(\displaystyle 20\textup{ feet}\) to the north. How far away from his starting point is he now?

Possible Answers:

\(\displaystyle 25\textup{ ft}\)

\(\displaystyle 45\textup{ ft}\)

\(\displaystyle 22\textup{ ft}\)

\(\displaystyle 35\textup{ ft}\)

\(\displaystyle 30\textup{ ft}\)

Correct answer:

\(\displaystyle 25\textup{ ft}\)

Explanation:

This is solving for the hypotenuse of a triangle. Using the Pythagorean Theorem, which says that \(\displaystyle a^2+b^2=c^2\) 

 \(\displaystyle 15^2 + 20^2 = c^2\) 

\(\displaystyle 225+400=c^2\)

\(\displaystyle 625=c^2\)

\(\displaystyle 25=c\)

 

Example Question #1311 : Basic Geometry

A right triangle has side lengths of 20 inches and 19 inches. What is the length of its hypotenuse?

Possible Answers:

\(\displaystyle H=27.6in\)

\(\displaystyle H=42.6in\)

\(\displaystyle H=36.6in\)

\(\displaystyle H=19in\)

None of these.

Correct answer:

\(\displaystyle H=27.6in\)

Explanation:

We can find any one missing side of a right triangle with the Pythagorean theorem. 

\(\displaystyle a^2+b^2=c^2\)

\(\displaystyle 19^2+20^2=c^2\)

\(\displaystyle 361+400=c^2\)

Simplify and take the square root of both sides:

\(\displaystyle \boldsymbol{c=27.6in}\)

Example Question #91 : How To Find The Length Of The Hypotenuse Of A Right Triangle : Pythagorean Theorem

Tri 2

Given the right triangle above, find the length of the hypotenuse.

Possible Answers:

\(\displaystyle 54\)

\(\displaystyle 17.32\)

\(\displaystyle 14.491\)

\(\displaystyle 22\)

\(\displaystyle 18.248\)

Correct answer:

\(\displaystyle 18.248\)

Explanation:

To find the length of the hypotenuse, we will use the Pythagorean Theorem

\(\displaystyle a^2+b^2=c^2\).  

In this formula, c represents the hypotenuse whereas a and b represent the base and height of the right triangle.  

So, first we must square the values of the given sides of the triangle.  

\(\displaystyle 3^2=9\) 

and 

\(\displaystyle 18^2=324\).  

Next, we must add these two solutions to get \(\displaystyle 333\).  

The hypotenuse will be the square root of this number, so using our calculator we can estimate the length of the hypotenuse to be the decimal: 

\(\displaystyle \sqrt{333}\approx18.248\).

Example Question #91 : How To Find The Length Of The Hypotenuse Of A Right Triangle : Pythagorean Theorem

Tri 1

Given the right triangle above, find the length of the hypotenuse.

Possible Answers:

\(\displaystyle 5.477\)

\(\displaystyle 15.553\)

\(\displaystyle 15\)

\(\displaystyle 19.643\)

\(\displaystyle 21.26\)

Correct answer:

\(\displaystyle 21.26\)

Explanation:

To find the length of the hypotenuse, we will use the Pythagorean Theorem

\(\displaystyle a^2+b^2=c^2\).  

In this formula, c represents the hypotenuse whereas a and b represent the base and height of the right triangle.  

So, first we must square the values of the given sides of the triangle.  

\(\displaystyle 14^2=196\) 

and 

\(\displaystyle 16^2=256\).  

Next, we must add these two solutions to get \(\displaystyle 452\).  

The hypotenuse will be the square root of this number, so using our calculator we can estimate the length of the hypotenuse to be the decimal: 

\(\displaystyle \sqrt{452}\approx21.26\).

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