Linear functions (1 Viewer)

[Joshmosh2]

If I have the origin, (0,0) and a random point along the y-axis, for example A (0,2) and am given point, for example P (-3,-1) how can I make an equation for line PB if B is perpendicular to OA?
In simpler terms, I want to find the perpendicular gradient of OA

 

[rumbleroar]

1. Find gradient of OA (simple rise-run formula will do)
2. Use the fact that when any two perpendicular gradients are multiplied, they equal -1. i.e. m_1 x m_2 = -1 and use that to figure out the value of the gradient of PB

 

[Joshmosh2]

1. Find gradient of OA (simple rise-run formula will do)
2. Use the fact that when any two perpendicular gradients are multiplied, they equal -1. i.e. m_1 x m_2 = -1 and use that to figure out the value of the gradient of PB

Hmm am I missing something? If you do the rise / run = 2/0 = undefined

 

[D94]

Think about what OA looks like. It's just a vertical straight line from the origin. So any line that is perpendicular to that must be a horizontal straight line, and in this case, it passes through point P.