X = 2COS(20ΠT − Π/2)CM; CÂU 40

Câu 87: 24m; Câu 88: cm; Câu 89: 1,5A; Câu 90:

3

π/2) cm; Câu 39: x = 2cos(20πt − π/2)cm; Câu 40: x x = 3cos(4 t + π/3) (cm); Câu 91: x = 5cos(20πt - π/4) cm; Câu 92: 6 cm; Câu 93: x = 5 cos(πt - π/4) = 2cos (10πt + π)cm; Câu 41: x = 0,3cos(5t − π/2)

2

(cm); cm; Câu 42: x = 4cos(10 t + π/3)cm; Câu 43: x = 6cos (t/3 − π/4)(cm); Câu 44: x = 10cos(πt +π/3)cm;