Which of the following formula is correct for Equivalent diameter for a triangular pitch?

• A. D = \(\frac{4(\frac{1}{2}πPt^2+\frac{\frac{1}{2}πOD^2}{8})}{\frac{1}{2}πOD^2}\)
• B. D = \(\frac{4(\frac{1}{2}πPt^2+\frac{\frac{1}{2}πOD^2}{4})}{\frac{1}{2}πOD^2}\)
• C. D = \(\frac{4(0.86\frac{1}{2}πPt^2-\frac{\frac{1}{2}πOD^2}{4})}{\frac{1}{2}πOD^2}\)
• D. D = \(\frac{4(\frac{0.86}{2}πPt^2-\frac{\frac{1}{2}πOD^2}{4})}{\frac{1}{2}πOD}\)