Question

If in a circle one angle is 120°, then what is the degree of other angle?

• A. 240°
• B. 40°
• C. 100°
• D. 340°

Hint:

The sum of angles around a single point is always 360°. If you are given one part of a circle, you can always find the "other part" by subtracting the given angle from 360°.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
The question is about the angles around the center of a circle. The total angle around a point (or the center of a circle) is a whole angle, which is 360°. The question implies the circle is divided into two sectors.
Step 2: Key Formula or Approach
Total angle in a circle = 360°.
If the circle is divided into two angles (Angle 1 and Angle 2), then:
\[ \text{Angle 1} + \text{Angle 2} = 360° \] Step 3: Detailed Explanation
Given that one angle is 120°. Let's call this Angle 1.
Angle 1 = 120°.
The "other angle" (Angle 2) would be the remaining part of the circle.
\[ 120° + \text{Angle 2} = 360° \] To find Angle 2, we subtract 120° from 360°:
\[ \text{Angle 2} = 360° - 120° \] \[ \text{Angle 2} = 240° \] This is also known as the reflex angle to the 120° angle.