Maths hw

The line L1 has equation 3x - y = 1 and the point P has coordinates (8,3)

a) Find the equation of the line L2 which passes through P and is perpendicular to line L1

b) Find the coordinates of the point Q where L1 and L2 intersect

c) find length PQ

Reply 1

mqb2766

Original post by Redratt909

The line L1 has equation 3x - y = 1 and the point P has coordinates (8,3)
a) Find the equation of the line L2 which passes through P and is perpendicular to line L1
b) Find the coordinates of the point Q where L1 and L2 intersect
c) find length PQ

What have you tried / stuck with?

Reply 2

username7381256

Original post by Redratt909

The line L1 has equation 3x - y = 1 and the point P has coordinates (8,3)
a) Find the equation of the line L2 which passes through P and is perpendicular to line L1
b) Find the coordinates of the point Q where L1 and L2 intersect
c) find length PQ

I will give you a hint:

a. rearrange the formula of L1 to get Y by itself and whatever the coefficient is, make sure the perpendicular line has the gradient which is the negative reciprocal. You can double check it the product of both of those gradients multiply to give -1. Then use the y - y1 = m(x-x1) to find the equation

b. solve the equations simultaneously after you found the equation of L2

c. Use Pythagoras theorem.

(edited 7 months ago)

Reply 3

Nitrotoluene

Original post by Redratt909

The line L1 has equation 3x - y = 1 and the point P has coordinates (8,3)
a) Find the equation of the line L2 which passes through P and is perpendicular to line L1
b) Find the coordinates of the point Q where L1 and L2 intersect
c) find length PQ

You must first find the slope of L1.