engineering mathematics MCQ #5527

If cos(x) = 3/5, what is cos(2x)?

engineering mathematics MCQ #5527

  1. Question 1

    Q1. If cos(x) = 3/5, what is cos(2x)?

    • A) 7/25
    • B) -7/25
    • C) 17/25
    • D) -17/25

    Answer: 7/25

    Explanation: Using cos(2x) = 2cos²(x) - 1, we find cos(2x) = 2(3/5)² - 1 = 2(9/25) - 1 = 18/25 - 25/25 = -7/25.