11(b) Since
VC  and VL are always along the same line and in
opposite directions, they can be combined into a single phasor (VC + VL)
which has a magnitude ½vCm – vLm½ Since V is represented as the
hypotenuse of a right-triangle whose sides are VR and (VC + VL), the
pythagorean theorem gives:
(
)
2
2
2
m
Rm
Cm
Lm
v
v
v
v
=
+
−
Substituting the values of vRm, vCm, and vLm from Eq (7