engineering mathematics MCQ #4946

The general solution of cos(x) + cos(3x) = 0 is

engineering mathematics MCQ #4946

  1. Question 1

    Q1. The general solution of cos(x) + cos(3x) = 0 is

    • A) nπ/2 + π/4
    • B) nπ + π/4
    • C) nπ ± π/4
    • D) nπ/2 ± π/4

    Answer: nπ/2 ± π/4

    Explanation: Using sum-to-product, 2cos(2x)cos(x) = 0, hence cos(2x) = 0 or cos(x) = 0, giving x = nπ/2 ± π/4 or (2n+1)π/2.