For a series RLC circuit, R=XL=2XC. The impedance of the circuit and phase difference between V and i will be
XL=R, XC=R/2
∴tanϕ=XL−XCR=R−R2R=12
⇒ϕ=tan−1(1/2)
Also, Z=R2+XL−XC2=R2+R24=52R