TeX source:

WCI = \left\{ \begin{array}{lll}T & \mbox { if  0 ≤ v ≤ 4 }\\ 91.4 – \dfrac{10.45 + 6.69 \sqrt v – 0.447v}{22} (91.5 – T) &  \mbox { if 4 ≤ v ≤ 45}\\ 1.60T – 55 & \mbox { if  v > 45} \end{array} \right.