45-45-90 and 30-60-90 Triangles

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Questions and Answers

A square's diagonal has a length of $7\sqrt{2}$. What is the area of the square?

  • 49 (correct)
  • 7
  • 98
  • 14

In a 30-60-90 triangle, the shortest side has a length of 5. What is the length of the hypotenuse?

  • 10 (correct)
  • $\frac{5\sqrt{3}}{2}$
  • $\frac{10\sqrt{3}}{3}$
  • 5\sqrt{3}

Given $\sin(\theta) = \frac{\sqrt{3}}{2}$ and $\cos(\theta) = \frac{1}{2}$, what is the value of $\tan(\theta)$?

  • 2
  • $\sqrt{3}$ (correct)
  • $\frac{\sqrt{3}}{3}$
  • 1

An equilateral triangle has a side length of 8. What is the exact area of the triangle?

<p>16$\sqrt{3}$ (B)</p> Signup and view all the answers

If $\cos(A) = \frac{5}{13}$, what is the value of $\sin(A)$ if $A$ is an acute angle in a right triangle?

<p>$\frac{12}{13}$ (D)</p> Signup and view all the answers

What is the simplified form of $\frac{8}{\sqrt{2}}$?

<p>4$\sqrt{2}$ (B)</p> Signup and view all the answers

In a right triangle, one angle measures 30°, and the hypotenuse has a length of 10. What is the length of the side opposite the 30° angle?

<p>5 (C)</p> Signup and view all the answers

If $\tan(\theta) = 1$, what is the measure of angle $\theta$ in degrees, assuming $0^\circ < \theta < 90^\circ$?

<p>45° (C)</p> Signup and view all the answers

An observer is standing 50 feet away from the base of a tree. The angle of elevation to the top of the tree is 60°. Approximately how tall is the tree?

<p>86.6 feet (C)</p> Signup and view all the answers

What is the value of $x$ in the expression $\frac{\sqrt{27x}}{\sqrt{3}} = 9$?

<p>27 (C)</p> Signup and view all the answers

Flashcards

Simplify and Rationalize

Simplifying involves reducing a fraction to its simplest form, while rationalizing removes radicals from the denominator.

45-45-90 Triangle Properties

45-45-90 triangles have sides in ratio x : x : x√2, where x is the length of each leg.

30-60-90 Triangle Properties

In a 30-60-90 triangle, sides are in ratio x : x√3 : 2x, where x is the shortest side.

Sine, Cosine, Tangent

Sine (sin) = Opposite / Hypotenuse, Cosine (cos) = Adjacent / Hypotenuse, Tangent (tan) = Opposite / Adjacent

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Area of a square given diagonal

Area = (diagonal^2) / 2

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Cosine Definition

In a right triangle, cosine of an angle = adjacent side / hypotenuse.

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Sine Definition

In a right triangle, sine of an angle = opposite side / hypotenuse.

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Tangent Definition

In a right triangle, tangent of an angle = opposite side / adjacent side.

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Study Notes

  • Self-assessment used to identify the strengths and weaknesses.
  • Practice problems used to review skills

Warm-Up Activity Skills

  • Properties of 45-45-90 triangles to find side lengths
  • Properties of 30-60-90 triangles to find side lengths
  • Simplify and rationalize answers
  • Estimate angle measures using trig ratios.
  • Calculate side lengths using cosine, sine, and tangent

Simplify and Rationalize Expressions

  • Examples simplifying and rationalizing expressions
  • Example a: 11/√5 simplified to (11√5)/5
  • Example b: 7/(2√2) simplified to (7√2)/4
  • Example c: (6/√3) simplified to 6√2
  • Example d: 3/√21 simplified to (√21)/7

Square's Diagonal and Area

  • Square's diagonal is 15.
  • Area of the square = x² = (15/√2)² = 225/2 = 112.5 units²

Triangle: Find x and y

  • Find the value of variables x and y in the triangle
  • 4 = x√2, so x = 4/√2 = 2√2; since it's a 45-45-90 triangle, x = y = 2√2

Triangle: Find a and b

  • b = 2√2
  • a = x√2 = 2√2 * √2 = 2 * 2 = 4

Find the Value of x and y in the Triangle

  • Solve for x and y
  • 12 = y√3, which gives y = 12/√3 = 4√3
  • x = 2y = 2 * 4√3 = 8√3

Equilateral Triangle

  • Equilateral triangle with side length of 12
  • Area calculation = bh = 6 * 6√3 = 36√3 units²

Solving for Variables in Diagrams

  • Diagram (a): x = 5√6 / 3
  • Diagram (b): x = 2√6
  • Diagram (c): x = 18√2
  • Diagram (d): x = 10

Estimating Trigonometric Values

  • Includes a table to estimate the values in order
  • Value A: adjacent leg/hypotenuse, opposite leg/hypotenuse, opposite leg/adjacent leg
  • Value B: adjacent leg/hypotenuse, opposite leg/hypotenuse, opposite leg/adjacent leg

Finding Hypotenuse Length

  • A right triangle, one angle is 50°, adjacent leg is 12 cm
  • cos(50°) = 12/x, which gives x ≈ 18.67 cm

Determining Opposite Length

  • Right triangle where one angle is 60°, adjacent leg is 16 cm
  • The length of the opposite is 16√3

Estimating Angle Measures

  • sin(θ) = 0.7245, θ is between 40° and 50°
  • cos(θ) = 0.9659, θ is between 10° and 20°
  • Tan(θ) = 3.7321, θ is between 70° and 80°
  • sin(θ) = 0.500, θ is 30°

Trigonometric Ratios

  • sin(J) = √2 / 3
  • cos(J) = 2√2 / 3
  • tan(J) = √2 / 4

Solving for Missing Sides

  • cos(36°) = x/7 which implies x = 5.7 units
  • sin(36°) = y/7 which implies y = 4.1 units

Solving for Missing Sides in Diagram

  • cos(12.7°) = 40/x which implies x = 41.0 units
  • tan(12.7°) = y/40 which implies y = 9.0 units

Calculating Distance

  • cos(51°) = A/8
  • Distance A ≈ 5.03 feet

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