Coordinate Geometry Fundamentals
The coordinate plane is divided into four quadrants (I, II, III, IV) by the x-axis and y-axis, which intersect at the origin. This system gives us a way to pinpoint exact locations using ordered pairs (x,y).
The Pythagorean Theorem a2+b2=c2 is the foundation for the distance formula, which lets you find the distance between any two points: d = √(x2−x1)2+(y2−y1)2. When you need to find the midpoint between two locations, use the midpoint formula: [(x1+x2)/2],[(y1+y2)/2] - just average the x-coordinates and y-coordinates.
When sketching graphs, follow these steps: isolate a variable when possible, create a table of values, plot the points, and connect them with a smooth curve or line. You can identify symmetry in three ways: x-axis symmetry x,−y, y-axis symmetry −x,y, or origin symmetry −x,−y.
Pro Tip: Test for symmetry algebraically by substituting -y for y x−axissymmetry, -x for x y−axissymmetry, or both -x and -y (origin symmetry). If you get an equivalent equation, symmetry exists!
The standard form of a circle equation is x−h² + y−k² = r², where (h,k) is the center and r is the radius. When the center is at the origin, this simplifies to x² + y² = r². This formula comes directly from applying the distance formula from the center to any point on the circle.