27. 如圖所示,請寫出此一波形的電壓方程式?(A) v(t) = 100sin(157t + 90°) V(B) v(t) = 100sin(157t – 90°) V(C) v(t) = 141.4sin(100t + 90°) V(D) v(t) = 100sin(100t – 90°) V