Unit circle

The unit circle

The unit circle has radius 1 centered at the origin. For angle θ: x = cos θ, y = sin θ. Key angles: 0°, 30°, 45°, 60°, 90° and their multiples. Memorize the pattern: sin(30°) = 1/2, sin(45°) = √2/2, sin(60°) = √3/2.