[u][b]Prove triangles are congruent.[/b][/u][br]It is easier to show congruent segments on the coordinate plane, rather than congruent angles.[br]SSS is the most common reason we will use to prove triangle are congruent on the coordinate plane.[br](If we have right triangles, we could also use SAS or HL.)
What information could be used to prove whether or not [math]\Delta ABC\cong\Delta DEF[/math]?
Prove whether or not [math]\Delta ABC\cong\Delta DEF[/math]
Since AB = 5.39 and DE = 5, [math]\overline{AB}[/math] is not congruent to [math]\overline{DE}[/math]. Therefore, [math]\Delta ABC[/math] is not congruent to [math]\Delta DEF[/math].
[u][b]Prove whether a triangle is a right triangle.[/b][/u][br]Since right angles are formed by perpendicular lines, we try to prove whether two of the triangle's sides are perpendicular.
Prove whether or not [math]\Delta DEF[/math] is a right triangle.
The slope of [math]\overline{DE}[/math] is 3.[br]The slope of [math]\overline{EF}[/math] is -1/4.[br]The slope of [math]\overline{DF}[/math] is -4/3.[br]Since none of the slopes are opposite reciprocals, [math]\Delta DEF[/math] is not a right triangle.