1. General Form of a Straight Line

Equation: Ax + By + C = 0

This is the general equation of a straight line, where:

• A, B, and C are constants
• x and y are variables representing coordinates on the graph

Example: Find the equation of a line passing through (2,3) and (4,7).

Step 1: Calculate values:

• A = (7 - 3) = 4
• B = -(4 - 2) = -2
• C = (4×3) - (2×7) = 12 - 14 = -2

Final Equation: 4x - 2y - 2 = 0

Enter Coefficients:

Plot Line

Formula: The area of a quadrilateral is:

Area = 0.5 × | x₁y₂ + x₂y₃ + x₃y₄ + x₄y₁ - (y₁x₂ + y₂x₃ + y₃x₄ + y₄x₁) |

Example: Find the area for points (1,2), (3,5), (6,4), (4,1).

Step 1: Apply the formula:

• Area = 0.5 × | (1×5 + 3×4 + 6×1 + 4×2) - (2×3 + 5×6 + 4×4 + 1×1) |
• Area = 0.5 × | (5 + 12 + 6 + 8) - (6 + 30 + 16 + 1) |
• Area = 0.5 × | 31 - 53 | = 0.5 × 22 = 11 square units

Enter Coordinates:

Calculate Area & Plot