Paper 3 June 2025, Question 10 10 marks
Express 2 sin x + 5 cos x in the form R sin (x + α)
where R > 0 and 0° ≤ α ≤ 90°
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In 2010, the water temperature at a beach could be modelled by the formula
T = 14.2 – (2 sin d ° + 5 cos d °)
where: T is the temperature of the water in °C
d is the number of days after 1 January 2010
Find the value of d when the temperature of the water reached its lowest value in 2010
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Find the maximum temperature of the water predicted by the model in 2010
Give your answer to one decimal place.
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Find the number of weeks in 2010 for which the temperature of the water was higher than 15 °C
Give your answer to the nearest whole number.
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