Question

What do we call 180\degree\ angle?

• A. Straight angle
• B. Obtuse angle
• C. Equilateral angle
• D. None of these

Hint:

Remember that a straight line forms a straight angle, which is exactly 180\degree.

Answer 1

The Correct Option is A

Step 1: Understanding angle classifications
Angles are classified based on their degree measures:
- Acute angle: Less than 90\degree
- Right angle: Exactly 90\degree
- Obtuse angle: More than 90\degree but less than 180\degree
- Straight angle: Exactly 180\degree

Step 2: Apply definition to given angle
Given angle = 180\degree
$\Rightarrow$ It matches the definition of a straight angle.

Step 3: Evaluate options
(A) Straight angle $\Rightarrow$ Correct
(B) Obtuse angle $\Rightarrow$ Between 90\degree and 180\degree, so incorrect
(C) Equilateral angle $\Rightarrow$ Not a standard term for individual angles, irrelevant here
(D) None of these $\Rightarrow$ Incorrect since (A) is correct
\[ \boxed{\text{Correct Answer: (A) Straight angle}} \]