Answer:
Part A: Angle R is not a right angle.
Part B; Angle GRT' is a right angle.
Step-by-step explanation:
Part A:
From the given figure it is noticed that the vertices of the triangle are G(-6,5), R(-3,1) and T(2,6).
Slope formula
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
The product of slopes of two perpendicular lines is -1.
Slope of GR is
[tex]\text{Slope of GR}=\frac{1-5}{-3-(-6)}=\frac{-4}{3}[/tex]
Slope of RT is
[tex]\text{Slope of RT}=\frac{6-1}{2-(-3)}=\frac{5}{5}=1[/tex]
Product of slopes of GR and RT is
[tex]\frac{-4}{3}\times 1=\frac{-4}{3}\neq -1[/tex]
Therefore lines GR and RT are not perpendicular to each other and angle R is not a right angle.
Part B:
If vertex T translated by rule
[tex](x,y)\rightarrow(x-1,y-2)[/tex]
Then the coordinates of T' are
[tex](2,6)\rightarrow(2-1,6-2)[/tex]
[tex](2,6)\rightarrow(1,4)[/tex]
Slope of RT' is
[tex]\text{Slope of RT'}=\frac{4-1}{1-(-3)}=\frac{3}{4}[/tex]
Product of slopes of GR and RT' is
[tex]\frac{-4}{3}\times \frac{3}{4}=-1[/tex]
Since the product of slopes is -1, therefore the lines GR and RT' are perpendicular to each other and angle GRT' is a right angle.