Examples with solutions for Using the Pythagorean Theorem: Isosceles triangle

Exercise #1

Triangle ABC is a right triangle,

Find X X XXABC

Step-by-Step Solution

To solve this problem, we need to determine the length of side X X in the right isosceles triangle ABC \triangle ABC with the hypotenuse 50 \sqrt{50} .

  • Step 1: Recall the Pythagorean theorem, which states that in a right triangle, the sum of the squares of the legs equals the square of the hypotenuse. For this isosceles case, where both legs X X are equal:
  • X2+X2=(50)2 X^2 + X^2 = (\sqrt{50})^2
  • Step 2: Simplify the equation:
  • 2X2=50 2X^2 = 50
  • Step 3: Solve for X2 X^2 by dividing each term:
  • X2=502=25 X^2 = \frac{50}{2} = 25
  • Step 4: Take the square root of both sides to solve for X X :
  • X=25=5 X = \sqrt{25} = 5

Therefore, the length of X X in the right isosceles triangle is 5 5 .

Answer

5 5

Exercise #2

The triangle in the drawing is rectangular and isosceles.

Calculate the length of the legs of the triangle.

AAABBBCCC

Video Solution

Step-by-Step Solution

We use the Pythagorean theorem as shown below:

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

Since the triangles are isosceles, the theorem can be written as follows:

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

We then insert the known data:

2AC2=(82)2=64×2 2AC^2=(8\sqrt{2})^2=64\times2

Finally we reduce the 2 and extract the root:

AC=64=8 AC=\sqrt{64}=8

BC=AC=8 BC=AC=8

Answer

8 cm

Exercise #3

The Egyptians decided to build another pyramid that looks like an isosceles triangle when viewed from the side.

Each side of the pyramid measures 150 m, while the base measures 120 m.

What is the height of the pyramid?

150150150120120120150150150

Video Solution

Step-by-Step Solution

Since the height divides the base into two equal parts, each part will be called X

We begin by calculating X:120:2=60 120:2=60

We then are able to calculate the height of the pyramid using the Pythagorean theorem:

X2+H2=1502 X^2+H^2=150^2

We insert the corresponding data:

602+h2=1502 60^2+h^2=150^2

Finally we extract the root: h=1502602=225003600=18900 h=\sqrt{150^2-60^2}=\sqrt{22500-3600}=\sqrt{18900}

h=3021 h=30\sqrt{21}

Answer

3021 30\sqrt{21} m

Exercise #4

Shown below is a rectangle and an isosceles right triangle.

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What is the area of the rectangle?

Video Solution

Step-by-Step Solution

To find the missing side, we use the Pythagorean theorem in the upper triangle.

Since the triangle is isosceles, we know that the length of both sides is 7.

Therefore, we apply PythagorasA2+B2=C2 A^2+B^2=C^2 72+72=49+49=98 7^2+7^2=49+49=98

Therefore, the area of the missing side is:98 \sqrt{98}

The area of a rectangle is the multiplication of the sides, therefore:

98×10=98.9999 \sqrt{98}\times10=98.99\approx99

Answer

99 \approx99

Exercise #5

Below is an isosceles right triangle:

XXXXXX161616

What is the value of X?

Video Solution

Answer

128 \sqrt{128}

Exercise #6

What is the area of the triangle in the figure?

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Video Solution

Answer

277 2\sqrt{77} cm²

Exercise #7

ABC is a right angled isosceles triangle.

What is the ratio of the length of the hypotenuse to the length of the leg?

BBBCCCAAA

Video Solution

Answer

2:1 \sqrt{2}:1

Exercise #8

Look at the triangles in the diagram below.

DBC is an isosceles triangle.

AB=13
AC=5

Calculate the length of the legs of triangle DBC.

131313555AAABBBCCCDDD

Video Solution

Answer

62 6\sqrt{2} cm

Exercise #9

Calculate AE given that triangle ABC is isosceles.

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Video Solution

Answer

813 8\frac{1}{3}

Exercise #10

The triangle in the figure is isosceles.

The length of the hypotenuse is x+32 \frac{x+3}{\sqrt{2}} cm.

Work out the length of the leg.

AAACCCBBB

Video Solution

Answer

x+32 \frac{x+3}{2} cm

Exercise #11

Below is an isosceles triangle drawn inside a circle:

What is the area of the circle?

Video Solution

Answer

π