# Is the answer choice I selected right?!

Mar 22, 2017

No. Your answer is not correct. The correct answer is B. See explanation.

#### Explanation:

The Y coordinates of $A '$, $B '$ and $C '$ are numbers opposite to the respective coordinates in $A$, $B$, and $C$, so the triangle $A ' B ' C '$ can be made from $A B C$ by reflection over $X$ axis.

Further, two triangles $A B C$ an A'B'Ç', the one when reflected over $x$-axis are always congruent as corresponding sides are equal and hence Answer D is wrong.

Mar 22, 2017

$\left(x , y\right) \to \left(x , - y\right)$

#### Explanation:

Let a corner (vertices) on a triangle be $P$
Let one triangle be $\text{a and the other triangle } b$

Given that there is a reflection about the x-axis and congruency exists;

then if ${P}_{a} \to \left({x}_{a} , {y}_{a}\right)$ then the corresponding point on the other triangle ${P}_{b} \to \left({x}_{b} , {y}_{b}\right) = \left({x}_{a} , - {y}_{a}\right)$

In other words the value of $x$ for corresponding vertices (corners) will be the same. However, the $y$ value in one will be $\left(- 1\right) \times y$ of the other.

So if one corner is $\left(- 1 , 7\right)$ then the other will be $\left(- 1 , - 7\right)$

So we have $\left(x , y\right) \to \left(x , - y\right)$

The $\to$ means 'maps to' or put another way; they are related in some way and there is some form of 'function' that links them.

Very loosely speaking, function is a mathematical term that can be interpreted as 'formula'