Question

find the value of k the line 5x+ky+78 is tangent to the circle x^2+y^2=36

Answer 1

The slope of tangent = dy/dx

2x + 2y dy/dx =0

dy/dx = -2x/2y= -x/y

tangent y = 2x - k

Have slope m= 2

-x/y = m =2

- x = 2y

k=5

k =-5

Hope helps