Answer:
a. Point C is at (8,8)
b. See image/expl
c. AngleABC = 140°
Explanation:
You can just count squares to find the slope of AD. To find points along AD, go
UP1 and OVER4
UP1 and OVER4 is the slope 1/4.
Start from B and go
UP1 and OVER4.
Parallel lines have the same slope. Perpendicular lines have slopes with opposite sign and "flipped". To make CD perpendicular to AD the slope should be -4/1 or 4/-1 is the same thing. To find C go from D
UP4 and BACK1
this is the slope 4/-1
1/4 and 4/-1 are negative reciprocals (opposite sign and flipped over) so the lines will be perpendicular.
You cab use this explanation for part b. Or you the slope calculations using the coordinates. See image.
part c, see image.