Ask a New Question
Menu

Prove or disprove the following identity:

(sin(10x))/(sin(x)+sin(9x)) = (cos(5x))/(cos4x))

1 answer

sin(x)+sin(9x) = 2sin(5x)cos(4x), so

sin(10x)/(2sin(5x)cos(4x)) = cos(5x)/cos(4x)
sin(10x)cos(4x) = 2cos(5x)sin(5x)cos(4x)
sin(10x)cos(4x) = sin(10x)cos(4x)
QED
Similar Questions
  1. please help me on the following:prove the identity. cos4x = 1-8sin^x2cos^2x
    1. answers icon 0 answers
  2. please help me on the following:prove the identity. cos4x = 1-8sin^x2cos^2x
    1. answers icon 1 answer
  3. Prove the identityCos⁴x + sin²x = sin⁴x + cos²x
    1. answers icon 1 answer
  4. Prove or disprove the following identity.cos(-x) - sin(-x) = cos(x) + sin(x)
    1. answers icon 1 answer
more similar questions