Question

Circle p is tangent to the x axis and the y axis. if the coordinates ofthe center are (r, r) find the equation of the line containing the points of tangency

A) x + y= r
B) x-y=r
C) x+y=1

Answer 1

I got y + x = r. My previous answer got deleted... but I'm just confirming they're correct. Also, I did the Odyssey assignment too.

The correct option is A.

Answer 2

we know that
Circle p is tangent to the x axis and the y axis
so
the point in the x axis is (0,r)
the point in the y axis is (r,0)

the equation of the line that containing the points of tangency is
point A(0,r) point B(r,0)
m=(y2-y1)/(x2-x1)------> m=(0-r)/(r-0)------> m=-r/r------> m=-1

with
m=-1 and point A(0,r)
y-y1=m(x-x1)-------> y-r=-1*(x-0)-----> y=-x+r--------> y+x=r

the answer is the option
A) x + y= r