Final answer:
The value of 'x' in a triangle is determined by using the Pythagoras theorem, while in a rectangle, it's determined by algebraic equations.
Step-by-step explanation:
In order to find the value of 'x' in both cases, we need to understand that two different concepts potentially apply; Pythagoras theorem for the triangle, and algebra for the rectangle. The Pythagorean theorem applies to right angle triangles and is expressed as x² + y² = h² where 'x' and 'y' are sides and 'h' is the hypotenuse. In a rectangle, to find 'x' related to an equation like y = 9 + 3x, you substitute values for 'y' and solve for 'x'. An example is given in Table A1 where we see an instance of substituting values for 'x' and then calculating what value of 'y' results. These points are then plotted on a graph.
Learn more about Pythagoras theorem and Algebra