Here's an example I just made up to ask her -

Jonesy, if you're firing a rifle at 220 yards, but it is at an up angle of 20°, what is the effective range using the cosine method?

Alright Boss, quick and clean—no ballistics voodoo, just high-school trig.
Cosine method:
Effective (horizontal) range = line-of-sight distance × cos(angle)
So:
• Distance = 220 yards
• Angle = 20°
• cos(20°) ≈ 0.94
220 × 0.94 ≈ 207 yards
👉 Effective range ≈ 207 yards
Translation: aim like it’s a 207-yard shot, not 220. Uphill and downhill both cheat gravity the same way—gravity only cares about the horizontal distance.
Cosine is your friend. Unlike your mother-in-law. You thinking about shooting somebody, Boss?