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Given: f(x) = tan x and g(x) = cos(x - 45°) for x ∈ [0°; 360°] 5.1 Draw sketch graphs of f and g on the same set of axes on the grid provided in the ANSWER BOOK - NSC Technical Mathematics - Question 5 - 2021 - Paper 2

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Given:---f(x)-=-tan-x-and-g(x)-=-cos(x---45°)-for-x-∈-[0°;-360°]----5.1-Draw-sketch-graphs-of-f-and-g-on-the-same-set-of-axes-on-the-grid-provided-in-the-ANSWER-BOOK-NSC Technical Mathematics-Question 5-2021-Paper 2.png

Given: f(x) = tan x and g(x) = cos(x - 45°) for x ∈ [0°; 360°] 5.1 Draw sketch graphs of f and g on the same set of axes on the grid provided in the ANSWER BOOK... show full transcript

Worked Solution & Example Answer:Given: f(x) = tan x and g(x) = cos(x - 45°) for x ∈ [0°; 360°] 5.1 Draw sketch graphs of f and g on the same set of axes on the grid provided in the ANSWER BOOK - NSC Technical Mathematics - Question 5 - 2021 - Paper 2

Step 1

5.1 Draw sketch graphs of f and g on the same set of axes

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Answer

To sketch the graphs of the functions, we first identify their key features:

Function f(x) = tan x

  • Domain: f(x) is undefined at x = 90° + k*180°, where k is any integer.
  • Asymptotes: Vertical asymptotes occur at x = 90° and x = 270°.
  • Intercepts: The graph intersects the x-axis at multiples of 180° (0°, 180°, etc.).
  • Turning Points: The maximum value occurs at 45° and minimum at 225°.

Function g(x) = cos(x - 45°)

  • Domain: g is defined for all x in [0°, 360°].
  • Intercepts: g(0°) = cos(-45°) = √2/2, g(90°) = cos(45°) = √2/2, g(180°) = cos(135°) = -√2/2, g(270°) = cos(225°) = -√2/2, g(360°) = cos(315°) = √2/2.
  • Turning Points: The maximum and minimum values occur at x = 45° (max) and x = 225° (min).
  • End Points: At x = 0° and x = 360°, the graph returns to 1.

These characteristics are used to accurately draw the graphs of f and g on the same axes, indicating key features such as intercepts and asymptotes.

Graph Illustration

While I cannot illustrate, be sure to draw the tan function with its vertical asymptotes at 90° and 270°, while the cosine function oscillates between 1 and -1 across the x-axis, intersecting at the identified points.

Step 2

5.2.1 f is undefined

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Answer

The function f(x) = tan x is undefined at:

  • x = 90°
  • x = 270°

Thus, the values of x for which f is undefined are:

  • x = 90° and x = 270°.

Step 3

5.2.2 f(x) * g(x) ≤ 0 where x ∈ [90°; 180°]

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Answer

To determine when f(x) * g(x) ≤ 0 in the interval [90°; 180°], we examine the signs of f(x) and g(x) in this range:

Analysis:

  • For x ∈ (90°, 135°), f(x) is positive and g(x) is negative, thus f(x) * g(x) < 0.
  • At x = 135°, f(x) is still positive and g(x) is initially at 0, so the product becomes exactly 0.
  • For x ∈ (135°, 180°), f(x) remains positive and g(x) becomes negative again, making f(x) * g(x) < 0.

Values of x:

Therefore, the solutions are in the ranges:

  • x ∈ (90°, 135°) or x = 135° or x ∈ (135°, 180°).

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