Answer:
[tex]y=-x+r[/tex]
Step-by-step explanation:
we know that
The tangency point on the x-axis is (r,0)
The tangency point on the y-axis is (0,r)
Find the slope of the line containing the points of tangency
[tex]m=\frac{0-r}{r-0}=-1[/tex]
Remember that the equation of the line into slope intercept form is equal to
[tex]y=mx+b[/tex]
where
m is the slope
b is the y-coordinate of the y-intercept
In this problem we have
[tex]m=-1[/tex]
[tex]b=r[/tex]
substitute
[tex]y=-x+r[/tex]