Question

1. choose the best answer.

which angle is a straight angle?
options: c, d, a, b (with diagrams a, b, c, d showing different angles)

Explanation:

A straight angle is an angle that measures 180 degrees and forms a straight line. Let's analyze each option:

• Option A: This is an acute angle (less than 90 degrees), not a straight angle.
• Option B: This is an obtuse angle (greater than 90 degrees but less than 180 degrees), not a straight angle.
• Option C: This is a right angle (measures 90 degrees), not a straight angle.
• Option D: The angle here forms a straight line, so it is a straight angle (180 degrees).

Answer:

D. The angle in option D forms a straight line, so it is a straight angle.