How do you find a standard form equation for the line with (8, -2) and perpendicular to the line whose equation is x-5y-7=0?
the basic equation of a straight line with known gradient
we are given a line perpendicular to the required line so we use the fact that if the gradient of the required line is
that is the product of the gradients of perpendicular lines is
so we use the line given to find the gradient
rearrange to the form
this is the perpendicular gradient
we also have
If the reader compares this with the original lines
a pattern may be seen .