I'm having some trouble with this question.

1. a) The line y = x -1 intersects the circle x^2 + y^2 = 25 at two points. This line is called a secant. Find the coordinates of the 2 points of intersection.

b) For what value(s) of k will the line y = x + k be a tangent to the circle x^2 + y^2 = 25?