Unit Circle Ca2705

1. **Problem Statement:** Understand what a unit circle is. 2. **Definition:** A unit circle is a circle with a radius of exactly $1$ unit. 3. **Formula:** The equation of a unit circle centered at the origin $(0,0)$ in the coordinate plane is: $$x^2 + y^2 = 1$$ 4. **Explanation:** This means any point $(x,y)$ on the unit circle satisfies this equation. 5. **Importance:** The unit circle is fundamental in trigonometry because it helps define sine, cosine, and tangent functions based on the coordinates of points on the circle. 6. **Summary:** The unit circle is a circle centered at the origin with radius $1$, described by the equation $x^2 + y^2 = 1$.