Which of the following lines is perpendicular to the horizon in standard position?

• A. A line with an angle of $180°$ measured from the positive x-axis
• B. A line with an angle of $90°$ measured from the positive x-axis
• C. A line with an angle of $0°$ measured from the positive x-axis
• D. A line with an angle of $45°$ measured from the positive x-axis

Answer: (B)

Verified step by step guidance

1. Understand that the horizon in standard position corresponds to the horizontal axis, which is the positive x-axis (0\degree) and its opposite direction (180\degree).
2. Recall that a line perpendicular to the horizon must be vertical, meaning it forms a 90\degree angle with the positive x-axis.
3. Identify the angle that represents a vertical line in standard position, which is 90\degree measured counterclockwise from the positive x-axis.
4. Compare the given options: 0\degree and 180\degree represent horizontal lines, 45\degree is an inclined line, and 90\degree is the vertical line perpendicular to the horizon.
5. Conclude that the line with an angle of 90\degree measured from the positive x-axis is perpendicular to the horizon.