engineering mathematics MCQ #5530

What is the value of cos(105°)?

engineering mathematics MCQ #5530

  1. Question 1

    Q1. What is the value of cos(105°)?

    • A) (√2 - √6)/4
    • B) (√2 + √6)/4
    • C) (√6 - √2)/4
    • D) -(√6 + √2)/4

    Answer: (√2 - √6)/4

    Explanation: Using cos(A + B) = cos(A)cos(B) - sin(A)sin(B), cos(105°) = cos(60° + 45°) = cos(60°)cos(45°) - sin(60°)sin(45°) = (1/2)(√2/2) - (√3/2)(√2/2) = (√2 - √6)/4.