23. Given , explain how to construct a square with sides of length AB.
24. Is the line through points P(–8, –10) and Q(–5, –12) perpendicular to the line through points R(9, –6) and S(17, –5)? Explain.

Question

23.   Given , explain how to construct a square with sides of length AB.
 24.   Is the line through points P(–8, –10) and Q(–5, –12) perpendicular to the line through points R(9, –6) and S(17, –5)? Explain.

anonymous · Answer

Perpendicular lines can be defined as one line being normal to the other. 
If line x is normal to line y, then line x will have a slope which is the negative reciprocal of the slope of line y.

Short version: find the slope of one of your lines, flip it over (switch the numerator & denominator) and put a negative in front of it. If that = the slope of your other line, they are perpendicular.