The period of the function \frac{\sin x + \sin 5x}{\cos x + \cos 5x} is -
Step-by-Step Solution
<div class="solution"><p>Need 2x≤-2 → x≤-1. g(x)=(2x+1)²+2. Minimum at x=-1: g(-1)=3. As x→-∞, g→∞. Range=[3,∞).</p><div class="trap-box"><strong>Trap:</strong> Don't minimize on all ℝ. Transfer domain restriction x≤-1 first.</div><div class="key-concept"><strong>Key Concept:</strong> Composition — always transfer old domain restriction to new variable</div></div>
Correct Answer: C