Ta có: \(\cos(\varphi)=\dfrac{R}{Z}\Rightarrow \cos\dfrac{\pi}{3}=\dfrac{30}{Z}\)
\(\Rightarrow Z = 60\Omega\)
Do i trễ pha với u nên u sớm pha \(\pi/3\) với i, ta có:
\(\tan\varphi=\dfrac{Z_L-Z_C}{R}\Rightarrow \tan\dfrac{\pi}{3}=\dfrac{70-Z_C}{30}\)
\(\Rightarrow Z_C=70-30\sqrt 3\approx 18\Omega\)