Final answer:
The topic 'RS Aggarwal Class 7 - Properties of Parallel Lines' is a Mathematics subject, specifically geometry, taught in middle school. It relates to linear equations and geometrical concepts such as vector addition using the parallelogram rule.
Step-by-step explanation:
The content described from 'RS Aggarwal Class 7 - Properties of Parallel Lines' pertains to the subject of Mathematics, specifically to a module typically taught in middle school. This module deals with Geometry, which is the branch of Mathematics concerned with the properties and relations of points, lines, surfaces, and solids. In the given context, the discussion revolves around linear equations, which are algebraic equations of the first degree (i.e., the highest power of the variable is one), and geometric applications like the parallelogram rule for vector addition.
From the example provided about the parallelogram rule, it is clear that the subject matter involves understanding how to construct the sum of two vectors using a geometric approach, a common practice in both geometry and physics. The specific topics mentioned, such as the 'parallax of C as viewed from AB' or the construction of isolines in an electric field, also indicate a focus on geometry-related problems and solutions.
To answer the linear equations question from '12.1 Linear Equations', all the given options A. y = -3x, B. y = 0.2 +0.74x, and C. y=-9.4 - 2x are linear equations because they are of the first degree in their variables. Therefore, the correct choice is D. A and B, which means both A and B are examples of linear equations.