Question

what is the value of cos(x+120)

Answer 1

Hey !!!

cos(A+B ) = cosA×cosB - sinA×sinB using this formula

cos(x+120° ) = cosx×cos120° - sinx×sin(120°)

=> cosx×cos(90°+30°) - sinx sin(90°+30°)

=> cosx(-cos30°) - sinx cos30°

=> -√3/2cosx - √3/2sinx [•°•cos30° =√3/2]

=> -√3/2 ( cosx + sinx) Answer


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Hope it helps you !!!


@Rajukumar111