Describe,in words ,how would you determine wether a triangle is a right triangle given its coordinates

if the dot product of two sides that has intersect is 0, then it's a right triangle

Variables:
y = time doing dance
x = time doing math
she spends 80 minutes every day practicing dance and math.
she spends 20 minutes more dancing than doing math.
  part a: write a pair of linear equations to show the relationship between the number of minutes pam practices math every day (x) and the number of minutes she practices dances every day (y).
x + y = 80
y = 20 +x
part b: how much time does pam spend on practicing math every day?
replace y in the firs equation with 20 + x
x + 20 + x = 80
2x = 60
x = 30 min
part c: is it possible for pam to have spent 60 minutes practicing dance every day? explain your reasoning.
no. as obtained in the part b, she practices math during 30 minutes; then, given that she spends 20 minutes more practicing dance, she spends only 30min + 20 min = 50 min practicing dance.