góc lõm

Góc lõm được tạo thành bởi hai tia chung gốc và phần mặt phẳng bên trong lớn hơn nửa mặt phẳng.

Definition

1. Noun (Geometry):
   • Reflex angle: An angle that measures greater than 180 degrees and less than 360 degrees. It is the larger angle formed when two lines or rays meet, representing the "outside" angle of a typical corner.

Usage Examples

• Noun:
  • Góc lõm thường ít gặp hơn góc nhọn trong các bài toán cơ bản. (Reflex angles are less common than acute angles in basic problems.)
  • Hãy đo góc lõm được tạo bởi hai cạnh này. (Please measure the reflex angle formed by these two sides.)
  • Tổng của một góc lồi và góc lõm tại một điểm là 360 độ. (The sum of a convex angle and a reflex angle at a point is 360 degrees.)

Advanced Usage

• In navigation or circular motion, a turn that goes beyond a half-circle (180°) but less than a full circle (360°) involves a reflex angle.
  • Con tàu đã rẽ một góc lõm để tránh cơn bão. (The ship turned through a reflex angle to avoid the storm.)

Variants and Related Words

• Góc lồi (n): Convex angle; an angle measuring between 0° and 180°, which is the more commonly referenced angle.
• Góc đầy (n): Full angle; an angle of exactly 360 degrees.
• Góc (n): Angle; the general term.

Synonyms

• Reflex angle: The direct and only precise geometric synonym.

Related Concepts

• Supplementary Angles: Two angles that add up to 180 degrees. The reflex angle and its associated convex angle (less than 180°) are supplementary to each other, as their sum is 360°.
• Protractor: The tool used to measure angles, including reflex angles. To measure a reflex angle directly, a protractor with a scale up to 360° is needed. Alternatively, one can measure the smaller convex angle and subtract it from 360°.