12. A(8, 2) and B(6, 4) are the vertices of a figure which is symmetrical about x = 6 and y = 2. Complete the figure and give the geometrical name of the figure.
12. A(8, 2) and B(6, 4) are the vertices of a figure which is symmetrical about x = 6 and y = 2. Complete the figure and give the geometrical name of the figure.

Solution:-

Steps for marking the points on graph:

1. As per the given data plot the points A(8, 2) and B(6, 8) on the graph.

2. Then plot point M whose vertices are x = 6 and y = 2.

3. Condition given the question, taking P as the point of symmetry.

4. So, point symmetric to A(8, 2) in the line x = 6 is C(4, 2)

5. Point symmetric to B(6, 4) in the line y = 2 is D(6, 0)

6. Now join AP, PC, BP and PD

By using the distance formula,

    \[AD\text{ }=\text{ }\surd ({{\left( 8\text{ }\text{ }6 \right)}^{2}}~+\text{ }{{\left( 2\text{ }\text{ }0 \right)}^{2}})\]

    \[=\text{ }\surd ({{2}^{2}}~+\text{ }{{2}^{2}})\]

    \[=\text{ }\surd \left( 4\text{ }+\text{ }4 \right)\]

    \[=\text{ }\surd 8\]

Then,

    \[AB\text{ }=\text{ }\surd ({{\left( 8\text{ }\text{ }6 \right)}^{2}}~+\text{ }{{\left( 2\text{ }\text{ }4 \right)}^{2}})\]

    \[=\text{ }\surd ({{2}^{2}}~+\text{ }(-{{2}^{2}}))\]

    \[=\text{ }\surd \left( 4\text{ }+\text{ }4 \right)\]

    \[=\text{ }\surd 8\]

So, from Pythagoras theorem

    \[B{{D}^{2}}~=\text{ }A{{D}^{2}}~+\text{ }A{{B}^{2}}\]

    \[{{4}^{2}}~=\text{ }{{\left( \surd 8 \right)}^{2}}~+\text{ }{{\left( \surd 8 \right)}^{2}}\]

    \[16\text{ }=\text{ }8\text{ }+\text{ }8\]

    \[16\text{ }=\text{ }16\]

Therefore, \angle BAD=90{}^\circ

Hence, it is clear that AB = BC = CD = DA, AC and BD bisect each other at right angles, so ABCD is a square.