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Vereenvoudig die volgende tot 'n enkele trigonometriese verhouding: 4.1 cos θ (tan θ + cot θ) 4.2 sin²(180° + B) · cosec (π - B) sec(2π - B) · cos(180° - B) - NSC Technical Mathematics - Question 4 - 2021 - Paper 1

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Vereenvoudig-die-volgende-tot-'n-enkele-trigonometriese-verhouding:--4.1-cos-θ-(tan-θ-+-cot-θ)--4.2--sin²(180°-+-B)-·-cosec-(π---B)-sec(2π---B)-·-cos(180°---B)-NSC Technical Mathematics-Question 4-2021-Paper 1.png

Vereenvoudig die volgende tot 'n enkele trigonometriese verhouding: 4.1 cos θ (tan θ + cot θ) 4.2 sin²(180° + B) · cosec (π - B) sec(2π - B) · cos(180° - B)

Worked Solution & Example Answer:Vereenvoudig die volgende tot 'n enkele trigonometriese verhouding: 4.1 cos θ (tan θ + cot θ) 4.2 sin²(180° + B) · cosec (π - B) sec(2π - B) · cos(180° - B) - NSC Technical Mathematics - Question 4 - 2021 - Paper 1

Step 1

4.1 cos θ (tan θ + cot θ)

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Answer

To simplify the expression, we begin with the trigonometric identities:

exttanθ=sinθcosθ ext{tan } θ = \frac{\sin θ}{\cos θ} and cot θ=1tan θ=cosθsinθ\text{cot } θ = \frac{1}{\text{tan } θ} = \frac{\cos θ}{\sin θ}.

Thus, we can rewrite the expression as:

ext{cost } θ (\text{tan } θ + \text{cot } θ) &= \cos θ \left(\frac{\sin θ}{\cos θ} + \frac{\cos θ}{\sin θ}\right) \\ &= \cos θ \left(\frac{\sin^2 θ + \cos^2 θ}{\sin θ \cos θ}\right) \\ &= \cos θ \cdot \frac{1}{\sin θ} \\ &= \frac{\cos θ}{\sin θ} \\ &= \text{cot } θ. \end{align*}$$

Step 2

4.2 sin²(180° + B) · cosec (π - B)

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Answer

For this part, we again use trigonometric identities:

  1. From the periodic properties, we know that: sin(180°+B)=sinB.\sin(180° + B) = -\sin B. Therefore, sin2(180°+B)=sin2B.\sin^2(180° + B) = \sin^2 B.

  2. The cosecant of an angle is the reciprocal of sine: cosec(πB)=1sin(πB)=1sinB.\cosec(π - B) = \frac{1}{\sin(π - B)} = \frac{1}{\sin B}. Combining these, we have: sin2(180°+B)cosec(πB)=sin2B1sinB=sinB.\sin^2(180° + B) · \cosec(π - B) = \sin^2 B · \frac{1}{\sin B} = \sin B.

  3. Next, we simplify the second expression: sec(2πB)cos(180°B).\sec(2π - B) · \cos(180° - B). Using the identities: sec(2πB)=secB\sec(2π - B) = \sec B and cos(180°B)=cosB.\cos(180° - B)= -\cos B. Thus, sec(2πB)cos(180°B)=secB(cosB)=1.\sec(2π - B) · \cos(180° - B) = \sec B · (-\cos B) = -1.

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