Coordinate Geometry

Master the intersection of Algebra and Geometry: Lines, Slopes, and Shapes on the Cartesian Plane.

1. The Cartesian Plane & Distance

<div class='space-y-4'> <p><strong>Quadrants:</strong></p> <ul class='list-disc pl-5 space-y-1 text-gray-600'> <li><strong>Q1 (+, +)</strong>: Top Right</li> <li><strong>Q2 (-, +)</strong>: Top Left</li> <li><strong>Q3 (-, -)</strong>: Bottom Left</li> <li><strong>Q4 (+, -)</strong>: Bottom Right</li> </ul> <div class='bg-primary-50 p-4 rounded-lg border-l-4 border-primary-500'> <h4 class='font-bold text-primary-700 mb-1'>Distance Formula</h4> <p>Distance between $A(x_1, y_1)$ and $B(x_2, y_2)$:</p> <div class='text-center text-lg font-bold text-gray-800 my-2'> $D = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$ </div> </div> </div>

2. Section Formula & Centroid

<div class='space-y-6'> <div class='grid grid-cols-1 md:grid-cols-2 gap-4'> <div class='bg-white p-4 rounded-xl border border-gray-200 shadow-sm'> <h5 class='font-bold text-primary-700 mb-2'>Internal Division (Ratio m:n)</h5> <p>$P(x, y) = \left( \frac{mx_2 + nx_1}{m+n}, \frac{my_2 + ny_1}{m+n} \right)$</p> </div> <div class='bg-white p-4 rounded-xl border border-gray-200 shadow-sm'> <h5 class='font-bold text-primary-700 mb-2'>Midpoint (Ratio 1:1)</h5> <p>$M(x, y) = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right)$</p> </div> </div> <div class='bg-primary-50 p-4 rounded-lg border-l-4 border-primary-500'> <h5 class='font-bold text-primary-700 mb-1'>Centroid of Triangle</h5> <p>Intersection of Medians:</p> <p class='text-center font-bold'>$G(x, y) = \left( \frac{x_1+x_2+x_3}{3}, \frac{y_1+y_2+y_3}{3} \right)$</p> </div> </div>

3. Area of Triangle (Shoelace Method)

<div class='space-y-4'> <p>For vertices $(x_1, y_1), (x_2, y_2), (x_3, y_3)$:</p> <div class='bg-red-50 p-4 rounded-lg text-center border border-red-200'> <p class='font-bold text-lg'>Area = $\frac{1}{2} | x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) |$</p> </div> <p class='text-sm text-gray-500'><strong>Note:</strong> If Area = 0, points are <strong>Collinear</strong> (Lie on the same line).</p> </div>

4. Slope & Equation of Line

<div class='space-y-4'> <ul class='list-none space-y-3'> <li class='bg-gray-50 p-3 rounded border-l-4 border-gray-500'> <strong>Slope ($m$):</strong> $m = \tan \theta = \frac{y_2 - y_1}{x_2 - x_1}$ </li> <li class='bg-gray-50 p-3 rounded border-l-4 border-gray-500'> <strong>Equation (Slope-Point):</strong> $y - y_1 = m(x - x_1)$ </li> <li class='bg-gray-50 p-3 rounded border-l-4 border-gray-500'> <strong>Standard Form:</strong> $ax + by + c = 0$ $\to$ Slope $= -a/b$ </li> </ul> <div class='grid grid-cols-2 gap-4 mt-2'> <div class='text-center p-2 bg-primary-100 rounded text-primary-800 font-bold'>Parallel Lines<br/>$m_1 = m_2$</div> <div class='text-center p-2 bg-red-100 rounded text-red-800 font-bold'>Perpendicular<br/>$m_1 \times m_2 = -1$</div> </div> </div>