Slope: Perpendicular Lines

Question

What is the slope of a line perpendicular to -1/2?

Answer 1

Since slope =rise/run, the perpendicular to the line with slope -1/2 would be its opposite, 2/1 or 2

Answer 2

The slopes of perpendicular lines are negative reciprocals of each other.  

 

So, a line perpendicular to a line with slope -1/2 has slope

-1/(-1/2) = 2.