Bueno, sabemos que:
$$ \ underline {\ text {Z}} _ {\ space \ text {in}} = \ frac {1} {\ frac {1} {4} + \ frac {1} {\ text {R}} + \ frac {1} {\ text {j} \ omega \ text {L}}} = \ frac {\ frac {1} {4} + \ frac {1 } {\ text {R}}} {\ left (\ frac {1} {4} + \ frac {1} {\ text {R}} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ text {L}} \ right) ^ 2} + \ frac {1} {\ left (\ frac {1} {4} + \ frac {1} {\ text {R}} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ text {L}} \ right) ^ 2} \ cdot \ frac {1} {\ omega \ text {L}} \ cdot \ text {j} \ tag1 $$
Entonces, sabes que sabes que:
$$ \ left | \ underline {\ text {I}} _ {\ space \ text {in}} \ right | = \ frac {\ left | \ underline { \ text {U}} _ {\ space \ text {in}} \ right |} {\ left | \ underline {\ text {Z}} _ {\ space \ text {in}} \ right |} = \ frac {\ left | \ underline {\ text {U}} _ {\ space \ text {in}} \ right |} {\ sqrt {\ left (\ frac {\ frac {1} {4} + \ frac {1 } {\ text {R}}} {\ left (\ frac {1} {4} + \ frac {1} {\ text {R}} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ text {L}} \ right) ^ 2} \ right) ^ 2 + \ left (\ frac {1} {\ left (\ frac {1} {4} + \ frac {1} {\ text {R }} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ text {L}} \ right) ^ 2} \ cdot \ frac {1} {\ omega \ text {L}} \ right) ^ 2}} \ tag2 $$
Y:
$$ \ left | \ underline {\ text {I}} _ {\ space2} \ right | = \ frac {\ left | \ underline {\ text {U} } _ {\ space \ text {in}} \ right |} {4} \ space \ Longleftrightarrow \ space \ left | \ underline {\ text {U}} _ {\ space \ text {in}} \ right | = 4 \ cdot \ left | \ underline {\ text {I}} _ {\ space2} \ right | \ tag3 $$
Y podemos escribir:
$$ \ left | \ underline {\ text {I}} _ {\ space1} \ right | = \ frac {\ left | \ underline {\ text {U} } _ {\ space \ text {in}} \ right |} {\ sqrt {\ left (\ frac {1} {\ text {R}} \ cdot \ frac {1} {\ left (\ frac {1} {\ text {R}} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ text {L}} \ right) ^ 2} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ text {L}} \ cdot \ frac {1} {\ left (\ frac {1} {\ text {R}} \ right) ^ 2 + \ left (\ frac {1} {\ omega \ texto {L}} \ derecha) ^ 2} \ derecha) ^ 2}} \ tag4 $$
Y recuerda que:
$$ \ left | \ underline {\ text {I}} _ {\ space1} \ right | = \ sqrt {2} \ cdot \ text {I} _ { \ space1 \ space \ text {rms}} \ tag5 $$
Y eso:
$$ \ omega \ text {L} = \ text {X} _ {\ space \ text {L}} \ tag6 $$