ra-đi-an
Definition
- Noun:
- Radian: A unit for measuring angles, defined as the angle subtended at the center of a circle by an arc whose length is equal to the circle's radius.
Usage Examples
- Noun:
- Một góc vuông bằng π/2 ra-đi-an. (A right angle is equal to π/2 radians.)
- Hãy đổi số đo góc này từ độ sang ra-đi-an. (Please convert this angle's measurement from degrees to radians.)
- Vận tốc góc thường được đo bằng ra-đi-an trên giây. (Angular velocity is often measured in radians per second.)
Advanced Usage
- "rad": The standard international symbol for radian, often used in scientific and technical writing instead of writing "ra-đi-an" in full.
- Góc quay là 1.5 rad. (The rotation angle is 1.5 rad.)
Variants and Related Words
- Độ (n): Degree, another common unit for measuring angles where a full circle is 360 degrees.
- Một đường tròn có 360 độ, tương đương 2π ra-đi-an. (A circle has 360 degrees, equivalent to 2π radians.)
Synonyms
- Angle unit: A general term for units like degrees, radians, or gradians.
Related Concepts
- Hàm lượng giác: Trigonometric functions (sine, cosine, tangent), which in calculus typically use radian measure as their input.
- Khi tính đạo hàm của sin(x), x phải được tính bằng ra-đi-an. (When calculating the derivative of sin(x), x must be in radians.)
- Độ dài cung: Arc length, which is simply the radius multiplied by the angle in radians (s = rθ).