26. 若兩交流電壓分別為：Va (t)=28.28sin(377t+30°)V、Vb (t)=14.14sin(377t+60°)V，則 Va (t)+Vb (t)之和應為多少？(A)41.2sin(377t+40°)V(B)29.1sin(377t+40°)V(C)41.2sin(377t+60°)V(D)29.1sin(377t+60°) V。