Respuesta :
cotxcos2x = 2cotx
cos2x = 2cotx/cotx
cos2x = 2
cos2x = 2cos²x - 1
2cos²x - 1 = 2
2cos²x = 2+1
2cos²x = 3
cos²x = 3/2
√cos²x = plus minus √(3/2)
cosx = plus minus √(3/2)
cos2x = 2cotx/cotx
cos2x = 2
cos2x = 2cos²x - 1
2cos²x - 1 = 2
2cos²x = 2+1
2cos²x = 3
cos²x = 3/2
√cos²x = plus minus √(3/2)
cosx = plus minus √(3/2)