Explanation:
PART 1:
on the graph you can make a triangle at any point and with any angle measures.
i recommend a smaller right triangle to be easiest.
i recommend the points (0,3) A (3,0) B and (0,0) C
∆ABC angle measurements:
m∠CAB=45°
m∠ABC=45°
m∠ACB=90°
PART 2:
(4,3) D (7,0) E and (4,0) F make an identical right triangle moved 4 squares to the right
m∠FDE=45°
m∠DEF=45°
to find the missing value of the angle EFD we will use subtraction and addition
180-(45+45)
180-90
90
therefore, the m∠EFD=90°
PART 3:
both the angle measures and the shapes of the triangles are the same
PART 4:
i used a 1:1 ratio
sorry for the wait :)