0580/21 Oct/Nov 2021, Question 20: Trigonometric Graphs and Equations
Cambridge IGCSE Mathematics 0580 · Paper 21 (Extended) · Calculator · 3 marks
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The question, in short
Solve the trigonometric equation 3(2 + cos x) = 5 for x in the interval 0° ≤ x ≤ 360°.
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Solution · 3 marks
- 12 + cos x = 5/3
- 2cos x = 5/3 − 2 = −1/3
- 3x = cos⁻¹(−1/3) = 109.47…°
- 4Other solution: x = 360 − 109.47… = 250.52…°
- 5x = 109.5°, 250.5°
Answer109.4 to 109.5 and 250.5 to 250.6
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Also searched as: 0580/21/O/N/21 · 0580_w21_qp_21 · 0580 w21 21 · question 20.
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