Examples with solutions for Using the Pythagorean Theorem: Applying the formula

Exercise #1

Look at the triangle in the diagram. How long is side AB?

222333AAABBBCCC

Video Solution

Step-by-Step Solution

To find side AB, we will need to use the Pythagorean theorem.

The Pythagorean theorem allows us to find the third side of a right triangle, if we have the other two sides.

You can read all about the theorem here.

Pythagorean theorem:

A2+B2=C2 A^2+B^2=C^2

That is, one side squared plus the second side squared equals the third side squared.

We replace the existing data:

32+22=AB2 3^2+2^2=AB^2

9+4=AB2 9+4=AB^2

13=AB2 13=AB^2

We find the root:

13=AB \sqrt{13}=AB

Answer

13 \sqrt{13} cm

Exercise #2

Consider a right-angled triangle, AB = 8 cm and AC = 6 cm.
Calculate the length of side BC.

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Step-by-Step Solution

To find the length of the hypotenuse BC in a right-angled triangle where AB and AC are the other two sides, we use the Pythagorean theorem: c2=a2+b2 c^2 = a^2 + b^2 .

Here, a=6 cm a = 6 \text{ cm} and b=8 cm b = 8 \text{ cm} .

Plugging the values into the Pythagorean theorem, we get:

c2=62+82 c^2 = 6^2 + 8^2 .

Calculating further:

c2=36+64 c^2 = 36 + 64

c2=100 c^2 = 100 .

Taking the square root of both sides gives:

c=10 cm c = 10 \text{ cm} .

Answer

10 cm

Exercise #3

Triangle ABC is a right triangle,

Find AC

55ABC

Step-by-Step Solution

To solve the problem, we'll follow these steps:

  • Step 1: Identify the given sides as the legs of the right triangle.
  • Step 2: Use the Pythagorean theorem, a2+b2=c2 a^2 + b^2 = c^2 , where the legs a a and b b are both 5 units.
  • Step 3: Calculate c c using the formula and determine AC.

Let's work through the solution in detail:
Step 1: We have a right triangle with sides AB=5 AB = 5 and BC=5 BC = 5 . These represent the legs of the triangle.

Step 2: According to the Pythagorean theorem, the hypotenuse AC=c AC = c can be calculated as follows:

a2+b2=c2 a^2 + b^2 = c^2
Substituting the values a=5 a = 5 and b=5 b = 5 :
52+52=c2 5^2 + 5^2 = c^2

Step 3: Calculate:

25+25=c2 25 + 25 = c^2
50=c2 50 = c^2
To find c c , take the square root of both sides:
c=50 c = \sqrt{50}

Therefore, the length of AC is 50 \sqrt{50} .

Answer

50 \sqrt{50}

Exercise #4

Triangle ABC is a right triangle,

Find AC

22ABC

Step-by-Step Solution

To find the hypotenuse AC AC in the right triangle ABC ABC , we will apply the Pythagorean Theorem. The theorem states that the square of the hypotenuse c c (which is the side opposite the right angle), is equal to the sum of the squares of the other two sides a a and b b .

Given that side AB=2 AB = 2 and BC=2 BC = 2 , we have:

  • a=2 a = 2
  • b=2 b = 2

According to the Pythagorean Theorem, c2=a2+b2 c^2 = a^2 + b^2 .

Substituting the given values into the theorem:

c2=22+22 c^2 = 2^2 + 2^2

c2=4+4 c^2 = 4 + 4

c2=8 c^2 = 8

To solve for c c , take the square root of both sides:

c=8 c = \sqrt{8}

Therefore, the length of the hypotenuse AC AC is 8\sqrt{8}.

Among the given choices, the correct answer is choice 2: 8 \sqrt8 .

Answer

8 \sqrt8

Exercise #5

Triangle ABC is a right triangle,

Find AC

71ABC

Step-by-Step Solution

To find the length of AC, the hypotenuse of the right triangle ABC, we will apply the Pythagorean Theorem:

The Pythagorean Theorem states:

a2+b2=c2 a^2 + b^2 = c^2 ,

where a a and b b are the legs (AB AB and BC BC ), and c c is the hypotenuse (AC AC ).
Given: AB=7 AB = 7 and BC=1 BC = 1 .

Substituting the given values into the theorem:

(7)2+(1)2=AC2 (7)^2 + (1)^2 = AC^2 .

Calculating the squares:

49+1=AC2 49 + 1 = AC^2 .

Simplifying the equation:

50=AC2 50 = AC^2 .

To find AC AC , take the square root of both sides:

AC=50 AC = \sqrt{50} .

Therefore, the length of AC is 50 \sqrt{50} .

Answer

50 \sqrt{50}

Exercise #6

Triangle ABC is a right triangle,

Find AC

1110ABC

Step-by-Step Solution

To solve the problem of finding the hypotenuse AC in right triangle ABC, we will use the Pythagorean theorem:

  • Step 1: Identify leg lengths. According to the problem, leg AB is 11 11 , and leg BC is 10 10 .
  • Step 2: Apply the Pythagorean theorem: a2+b2=c2 a^2 + b^2 = c^2 .
  • Step 3: Substitute the known values: 112+102=AC2 11^2 + 10^2 = AC^2 .
  • Step 4: Calculate: 121+100=AC2 121 + 100 = AC^2 .
  • Step 5: Simplify: 221=AC2 221 = AC^2 .
  • Step 6: Take the square root of both sides to solve for AC: AC=221 AC = \sqrt{221} .

Therefore, the length of AC is 221 \sqrt{221} .

Answer

221 \sqrt{221}

Exercise #7

Triangle ABC is a right triangle,

Find AC

618ABC

Step-by-Step Solution

To solve this problem, we'll apply the Pythagorean theorem to find the hypotenuse AC AC of the right triangle ABC \triangle ABC .

According to the Pythagorean theorem:
a2+b2=c2 a^2 + b^2 = c^2

Here, a=AB=6 a = AB = 6 and b=BC=18 b = BC = 18 are the legs of the triangle, and c=AC c = AC is the hypotenuse.

Substitute these values into the formula:
62+182=AC2 6^2 + 18^2 = AC^2

Calculate each square:
62=36 6^2 = 36
182=324 18^2 = 324

Add the squares of the legs:
36+324=360 36 + 324 = 360

Thus,
AC2=360 AC^2 = 360
Taking the square root of both sides gives:
AC=360 AC = \sqrt{360}

Therefore, the length of AC AC is 360\sqrt{360}.

Answer

360 \sqrt{360}

Exercise #8

Triangle ABC is isosceles,

Find AC

8020ABC

Step-by-Step Solution

To solve for the hypotenuse AC AC in triangle ABC \triangle ABC , we'll use the Pythagorean theorem:

  • Step 1: Identify sides: In the isosceles right triangle, let AB=80 AB = 80 , BC=20 BC = 20 . These are the two legs.
  • Step 2: Substitute into the Pythagorean theorem: AB2+BC2=AC2 AB^2 + BC^2 = AC^2 .
  • Step 3: Perform calculations:

Substitute the values into the equation:
802+202=AC2 80^2 + 20^2 = AC^2 .

Calculate each square value:
6400+400=AC2 6400 + 400 = AC^2 .

Combine the values:
6800=AC2 6800 = AC^2 .

To solve for AC AC , take the square root of both sides:
AC=6800 AC = \sqrt{6800} .

Therefore, the solution for the length of AC AC is 6800 \sqrt{6800} .

Answer

6800 \sqrt{6800}

Exercise #9

Triangle ABC is a right triangle,

Find AC

65ABC

Step-by-Step Solution

To solve this problem, we will use the Pythagorean Theorem. It states that for a right triangle with sides a a and b b , and hypotenuse c c , the relationship is given by:

a2+b2=c2 a^2 + b^2 = c^2

In triangle ABC, let AB=a=6 AB = a = 6 and BC=b=5 BC = b = 5 . We need to find the length of the hypotenuse AC=c AC = c .

Applying the Pythagorean Theorem, we have:

62+52=c2 6^2 + 5^2 = c^2

36+25=c2 36 + 25 = c^2

61=c2 61 = c^2

To find c c , we take the square root of both sides:

c=61 c = \sqrt{61}

Thus, the length of AC is 61 \sqrt{61} .

Answer

61 \sqrt{61}

Exercise #10

Triangle ABC is a right triangle,

Find AC

83ABC

Step-by-Step Solution

To solve for the length of side AC of triangle ABC, we will use the Pythagorean theorem as follows:

  • Step 1: Identify the sides - Side AB is 8 units and side BC is 3 units.
  • Step 2: Apply the Pythagorean theorem - a2+b2=c2 a^2 + b^2 = c^2 where c c is the hypotenuse.
  • Step 3: Substitute the lengths into the formula - 32+82=AC2 3^2 + 8^2 = AC^2 .
  • Step 4: Calculate - 9+64=AC2 9 + 64 = AC^2 .
  • Step 5: Simplify - 73=AC2 73 = AC^2 .
  • Step 6: Solve for AC - AC=73 AC = \sqrt{73} .

Therefore, the length of side AC in triangle ABC is 73 \sqrt{73} .

Answer

73 \sqrt{73}

Exercise #11

Triangle ABC is a right triangle,

Find AC

103ABC

Step-by-Step Solution

To find the length of side AC AC in the right triangle ABC \triangle ABC , we'll use the Pythagorean Theorem:

  • Step 1: Identify the given sides. Side AB=3 AB = 3 , and hypotenuse BC=10 BC = 10 .
  • Step 2: Apply the Pythagorean Theorem: AC2=AB2+BC2 AC^2 = AB^2 + BC^2 .
  • Step 3: Substitute the known values: AC2=32+102=9+100=109 AC^2 = 3^2 + 10^2 = 9 + 100 = 109 .
  • Step 4: Solve for AC AC : AC=109 AC = \sqrt{109} .

Upon calculating, we find that the length of AC AC is 109 \sqrt{109} .

This length corresponds to choice 3 from the provided options.

Thus, the solution to this problem is AC=109 AC = \sqrt{109} .

Answer

109 \sqrt{109}

Exercise #12

Triangle ABC is a right triangle,

Find AC

83ABC

Step-by-Step Solution

To solve this problem, we'll use the Pythagorean Theorem.

  • Step 1: Identify the sides: AB=8 AB = 8 , BC=3 BC = 3 .
  • Step 2: Use the formula: a2+b2=c2 a^2 + b^2 = c^2 , where c c is the hypotenuse (AC).
  • Step 3: Plug in the values: 32+82=AC2 3^2 + 8^2 = AC^2 .
  • Step 4: Calculate: 9+64=AC2 9 + 64 = AC^2 .
  • Step 5: Simplify: 73=AC2 73 = AC^2 .
  • Step 6: Solve for AC AC : AC=73 AC = \sqrt{73} .

Thus, the length of AC is 73 \sqrt{73} .

Answer

73 \sqrt{73}

Exercise #13

Triangle ABC is a right triangle,

Find m m

21mABC

Step-by-Step Solution

To find the length of the hypotenuse m m in right triangle ABC \triangle ABC , we will use the Pythagorean Theorem: a2+b2=c2 a^2 + b^2 = c^2 , where a a and b b are the lengths of the legs and c c is the hypotenuse.

  • Step 1: Identify the lengths of the legs. Here, a=2 a = 2 and b=1 b = 1 .
  • Step 2: Apply the Pythagorean Theorem: (2)2+(1)2=m2 (2)^2 + (1)^2 = m^2 .
  • Step 3: Calculate: 4+1=5 4 + 1 = 5 .
  • Step 4: Solve for m m by taking the square root: m=5 m = \sqrt{5} .

Therefore, the length of the hypotenuse m m is 5 \sqrt{5} .

This matches the provided answer choice: 5 \sqrt{5} (choice 4).

Answer

5 \sqrt{5}

Exercise #14

Look at the triangle in the diagram. Calculate the length of side AC.

333444AAABBBCCC

Video Solution

Step-by-Step Solution

To solve the exercise, we have to use the Pythagorean theorem:

A²+B²=C²

 

We replace the data we have:

3²+4²=C²

9+16=C²

25=C²

5=C

Answer

5 cm

Exercise #15

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What is the length of the hypotenuse?

Video Solution

Step-by-Step Solution

We use the Pythagorean theorem

AC2+AB2=BC2 AC^2+AB^2=BC^2

We insert the known data:

32+42=BC2 3^2+4^2=BC^2

9+16=BC2 9+16=BC^2

25=BC2 25=BC^2

We extract the root:

25=BC \sqrt{25}=BC

5=BC 5=BC

Answer

5

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