The direct cosine m is given by formula cosф= ____

• A. \(\frac{x_2-x_1}{l_e}\)
• B. \(\frac{y_2-y_1}{l_e}\)
• C. \(\frac{x_1-y_1}{l_e}\)
• D. \(\frac{x_2-y_2}{l_e}\)