special right triangles chapter 8 section 3 learning goal: use properties of 45°-45 °-90 °, and...

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Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles We make a living by what we get, but we make a life by what we give. -- Winston Churchill

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Page 1: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

Special Right Triangles

Chapter 8 Section 3

Learning Goal: Use properties of 45°-45 °-90 °, and

30 °-60 °-90 ° Triangles

We make a living by what we get, but we make a life by what we give. -- Winston

Churchill

Page 2: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

45°-45°-90° Triangles Special Right Triangle

x

x d d2 = x2 + x2

d2 = 2x2Simplify:

√d2 = √ 2x2

d = x√ 2

Three sides of lengths x, x, x√2

What did we learn about

ratios of sides?

Ratio of a 45°-45°-90° triangle is:

1 : 1 : √2

45°

Page 3: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

45°-45°-90° Triangles

Find the missing side

a = 4√2 cm

6√245°

6

Page 4: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

45°-45°-90° Triangles

38

45°21

14

Page 5: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

Special Right TrianglesWALLPAPER TILING The wallpaper in the figure can be divided into four equal square quadrants so that each square contains 8 triangles. What is the area of one of the squares if the hypotenuse of each 45°–45°–90° triangle measures millimeters?

A = 24.5 mm

Page 6: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

30°-60°-90° TrianglesConsider an equilateral ∆

2x

x

2x

x

a

60° 60°

30°

a2 = (2x)2 – x2

Simplify: a2 = 4x2 – x2

a2 = 3x2

√a2 = √3x2

a = x√3Three sides of lengths x, 2x, x√3

Ratios of sides?

Ratio of a 30°-60°-90° triangle is:

1 : √3 : 2

Page 7: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

30°-60°-90° Triangles

Find the missing sides

60°

30°5

10

5√3

8√33

4

Page 8: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

30°-60°-90° Triangles

68

30°

4√2

60°

60°

Find the Altitude of the Δ

Page 9: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

Special Right Triangles

Refer to the figure. Find x and y.

Page 10: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

Special Right Triangles

60 cm

The length of the diagonal of a square is cm. Find the perimeter of the square.

Page 11: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

Special Right Triangles

The side of an equilateral triangle measures 21 inches. Find the length of an altitude of the triangle.

Page 12: Special Right Triangles Chapter 8 Section 3 Learning Goal: Use properties of 45°-45 °-90 °, and 30 °-60 °-90 ° Triangles  We make a living by what we

Homework

Special Right Triangles 45-45-90, 30-60-90