Coordinate Geometry Coordinate Geometry 1. Midpoint and Length of a Line Segment The midpoint \(M\) of a line segment joining points \(P(x_1, y_1)\) and \(Q(x_2, y_2)\) is given by: \( M = \left(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\right) \) The length of the line segment \(PQ\) is: \( \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \) 2. Gradient of a Line The gradient (slope) of the line joining the points \(P(x_1, y_1)\) and \(Q(x_2, y_2)\) is: \( \frac{y_2 - y_1}{x_2 - x_1} \) 3. Parallel and Perpendicular Lines For parallel lines, the gradients \(m_1\) and \(m_2\) are equal: \( m_1 = m_2 \) For perpendicular lines, the product of their gradients is: \( m_1 \times m_2 = -1 \) 4. Equation of a Straight Line The equation of a straight line with gradient \(m\) passing through point \((x_1, y_1)\) is: \( y - y_1
