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Coordinate Geometry: Area of Triangle with Vertex at Origin
Area of blue triangle OPQ = area of red rectangle minus the area of the outer three triangles. = x2y1 – ½ [ (x1 y1 ) + (y2 -y1 )(x1 -x2 ) + (x2 y2 )] = x2y1 – ½ [ x1 y1 + x1 y2 – …