What is the sum of angles in a straight line?

• A. 90 degrees
• B. 180 degrees
• C. 360 degrees
• D. 270 degrees

Answer: (B)

The sum of angles in a straight line is 180 degrees. This concept comes from the basic properties of geometry, specifically relating to angles formed by intersecting lines. When two angles are adjacent and form a straight line, their measures add up to 180 degrees. This is because a straight line is essentially the angle formed by rotating from one end of the line to the other end, which represents half of a complete circle (360 degrees).

Therefore, the two angles on a straight line create a supplementary angle relationship, which means that together they complete the straight angle of 180 degrees. This fundamental property is crucial in various applications in geometry and trigonometry, ensuring that one can effectively work with angles and their relationships.