Veda Bites are swipeable micro-lessons — each one teaches exactly one
idea. Here's a taste from this kit; the app has the full deck.
💡 Key Idea
Two numbers locate anything
One number pins a point on a line. How many does a flat surface need?
Fix a starting point and two directions at right angles, and every position on a flat surface is captured by exactly two numbers — no more, no fewer.
↳ A plane is two-dimensional, so it takes exactly two numbers to place a point on it.
📖 Definition
Axes, origin, plane
The two lines everything else is measured from.
↳ Two perpendicular number lines and their crossing point set up the whole system.
⚠️ Common Mistake
The x-coordinate is measured from the y-axis
Almost everyone gets this backwards the first time.
To say how far right a point is, you must measure from the vertical line. So the x-coordinate is the distance from the y-axis, and the y-coordinate is the distance from the x-axis.
↳ Each coordinate is measured from the axis it is not named after.
💡 Key Idea
Hide a right triangle under the segment
Two points sit at a slant. No single subtraction will measure that gap.
Run a horizontal line from one point and a vertical line from the other. They meet, and the three points form a right-angled triangle whose hypotenuse is the segment you want.
↳ Every distance question on the plane is a right-triangle question in disguise.
⭐ Important Fact
Baudhāyana and Pythagoras
The theorem behind the formula has two names for a reason.
The square on the hypotenuse equals the sum of the squares on the other two sides.
↳ The rule that turns two legs into a hypotenuse is what makes the distance formula work.
➗ Formula
The distance formula
One line that measures any gap on the plane.
For $A(x_1, y_1)$ and $B(x_2, y_2)$:
↳ Differences, squares, sum, square root — in that order, every time.