Cross-sectional area of 1st armour

Symbol
$A_{a_{1}}$
Unit
mm$^2$
Formulae
$\frac{d_{f_{1}}^{2} n_{a_{1}} \pi}{4}$round wires
$d_{f_{1}} n_{a_{1}} w_{f_{1}}$flat wires
$\pi \left(- \left(\frac{d_{a_{1}}}{2} - \frac{d_{f_{1}}}{2}\right)^{2} + \left(\frac{d_{a_{1}}}{2} + \frac{d_{f_{1}}}{2}\right)^{2}\right)$TECK, steel tapes
Related
$A_{a_{2}}$
$d_{f_{1}}$
Used in
$A_{a}$