Update FOC_routine.md

Author: askuric

docs/simplefoc_library/digging_deeper/theory/FOC_routine.md

@@ -50,9 +50,10 @@ Sinusoidal modulation is based on two transformation equations.
 <img src="../extras/Images/foc_modulation.png" >
 
 Inverse Park transformation:<br>
-<img src="../extras/Images/inverse_park.png" style="margin-left:50px;margin-top:10px;margin-bottom:10px;width:150px"><br>
+$$U_{\alpha} = U_q sin(\theta)$$
+$$U_{\beta} = U_q cos(\theta)$$
+
 Inverse Clarke transformation:<br>
-<img src="../extras/Images/inverse_clarke.png" style="margin-left:50px;margin-top:10px;margin-bottom:10px;width:180px">
 
 $$u_a = U_{\alpha}$$