k i am a grade 11 student and need help with some questions

These question are from Grade 11 Nelson Book (Canadian) From a quadratic section

1a) 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 two points of intersection.

1b) For what value(s) of k will the line y = x + k be a tangent to the circle x^2 + y^2 = 25? A tangent is a line that touches a circle exactly one point.

2) vitaly and jen have 24 m of fencing to enclose a vegetable garden at teh back of their house. What are the dimensions of the largest rectangular garden they could enclose with the length of fencing?

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