给上述图表，增加网格线，图例，并依次标注（annoate/text）三个曲线的均值， 方差等信息

以下是增加网格线、图例，并标注三个曲线的均值、方差等信息后的图表：

import matplotlib.pyplot as plt
import numpy as np

# 生成数据
x = np.linspace(0, 10, 100)
y1 = np.sin(x)
y2 = np.cos(x)
y3 = np.tan(x)

# 绘制图表
fig, ax = plt.subplots()
ax.plot(x, y1, label='sin(x)')
ax.plot(x, y2, label='cos(x)')
ax.plot(x, y3, label='tan(x)')

# 添加网格线
ax.grid(True)

# 添加图例
ax.legend(loc='upper right')

# 标注信息
ax.annotate(f"Mean: {np.mean(y1):.3f}\nStd: {np.std(y1):.3f}", xy=(8, 0), xytext=(8, 0.5),
            arrowprops=dict(facecolor='black', shrink=0.05))
ax.annotate(f"Mean: {np.mean(y2):.3f}\nStd: {np.std(y2):.3f}", xy=(3, 0), xytext=(3, -0.5),
            arrowprops=dict(facecolor='black', shrink=0.05))
ax.annotate(f"Mean: {np.mean(y3):.3f}\nStd: {np.std(y3):.3f}", xy=(2.5, 5), xytext=(4, 5),
            arrowprops=dict(facecolor='black', shrink=0.05))

plt.show()