kosinus kąta 3x Nienor: cos3α=Re(cos3α+isin3α)=Re(cosα+isinα)³=Re(cos³α+3cos²α*isinα+3(isinα)²cosα+(isinα)³)= Re(cos³αα+3cos²α*isinα−3sin²αcosα−isin³α)=cos³α−3sin²αcosα