ACT Preparation / Unit 9 ACT 0802 short lesson, about 20 seconds
The Distance Formula
Captions available
The idea
The distance between (x₁, y₁) and (x₂, y₂) is √((x₂ − x₁)² + (y₂ − y₁)²): the Pythagorean theorem applied to the horizontal and vertical gaps.
In practice
From (1, 2) to (4, 6): √(3² + 4²) = √25 = 5.
Where people slip
Square before adding, and add before taking the root. The order of the points does not matter, because squaring removes the signs.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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