What is sin 30°?

**The reasoning** sin 30° is a special angle value you need to memorize, but let's see *why* it's ½. Imagine an equilateral triangle with all sides = 2 units. All angles = 60°. Now cut it in half vertically. You get two right-angled triangles. Each has: - Hypotenuse = 2 (original side) - Base = 1 (half of the bottom) - Height = √3 (by Pythagoras: 2² − 1² = 3, so √3) - Angles: 30°, 60°, 90° Since sin = opposite/hypotenuse, and the side opposite the 30° angle is 1: sin 30° = 1/2 = **½** ✓ **Why the wrong options tempt you** **B) √3/2** — That's sin 60° or cos 30°. Easy to mix up the 30-60 pair! **C) 1** — That's sin 90°. Students sometimes guess the "nice" number. **D) 0** — That's sin 0°. Completely different angle. **Quick takeaway** For JAMB/WAEC: memorize the 30-60-90 triangle ratio (1 : √3 : 2) — sin 30° = ½, cos 30° = √3/2, and they swap for 60°.