Question 19
In the figure given, we have 16 points forming a square reticulated and two straight lines, $r$ and $s$, perpendicular to each other. 
a) How many squares can we build, in such a way that its vertices belong to the lattice, but none of its sides is parallel, nor to the line $r$, nor to the line $s$ ?
b) How many isosceles right triangles we can build in such a way that their vertices belong to the lattice, but none of its sides are parallel, nor to the line $r$, nor to the straight $s$ ?
a) How many squares can we build, in such a way that its vertices belong to the lattice, but none of its sides is parallel, nor to the line $r$, nor to the line $s$ ?
b) How many isosceles right triangles we can build in such a way that their vertices belong to the lattice, but none of its sides are parallel, nor to the line $r$, nor to the straight $s$ ?