2025 CGSS PRELIMS P1 Q11

2025 CGSS PRELIMS P1 Q11

Secondary 4
10 marks
  1. Prove that \(\dfrac{\tan x}{1+\sec x}+\dfrac{1+\sec x}{\tan x}=2\cosec x\).[4]
  2. Hence, solve \(\dfrac{\tan 2x}{1+\sec 2x}+\dfrac{1+\sec 2x}{\tan 2x}=3\sec x\) for \(-\pi \leq x \leq \pi\).[4]
  3. Use the result in part (a) to find the range of values of \(k\) for which the equation \( \dfrac{\tan x}{1+\sec x}+\dfrac{1+\sec x}{\tan x}=k \) has no solutions.

    [2]

Solution:

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Answer:(b) \(x=0.340\text{ rad}\) or \(2.80\text{ rad}\) (c) \(-2\le k\le2\)

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