All of the adjacent sides of quadrilaterals have slopes with a product of -1 True or false?

What do you think, and why?

Here's a hint: the slopes of two lines that are perpendicular to each other are the negative inverse of each other. In other words if the slope of one line is 'm,' then the slope of a line that is perpendicular to it is -1/m. What does this mean for the product of the slopes of perpendicular lines? And how does this apply to adjacent sides of quadrilaterals?