WAEC Mathematics 2014 Theory — Question 20

Question 20 of 23 from the West African Examinations Council (WAEC) Mathematics 2014 Theory paper, with the correct answer and a full explanation.

12(a). Given that 5cos(x+8.5)°−1=0, 0°≤x°≤90°, calculate, correct to the nearest degree, the value of x.

Model answer

5cos(x+8.5)°=1 cos(x+8.5)° = 0.2 x+8.5° = cos⁻¹(0.2) = 78.46° x = 78.46−8.5 ≈ 70° (to the nearest degree)

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