A (x:y)
4.1.1 Determine the coordinates of A, the centre of the circle and the length of the
radius, r.
4.1.2
4.1.3
Calculate the value of p if N (1; p) with p>0 is a point on the circle.
Determine the equation of the tangent to the circle at N.
A second circle, centre B, with equation (x-4)² + y² = k² cuts the circle given
in (4.1) twice. Determine the values of k for which point A will be inside the circle B.
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Verified Answer :

Let's solve the given questions step-by-step:

### 4.1.1 Determine the coordinates of A, the centre of the circle and the length of the radius, r.

Let’s assume the center of the circle, \(\( A(x, y) \)\), is \(\( (a, b) \)\) and it has a radius \(\( r \)\).

### 4.1.2 Calculate the value of p if \(\( N(1, p) \)\) with \(\( p > 0 \)\) is a point on the circle.

Since point \(\( N(1, p) \)\) lies on the circle, it must satisfy the equation of the circle. Using the distance formula between points \(\( (a, b) \)\) and \(\( (1, p) \)\):

\(\[ \sqrt{(a - 1)^2 + (b - p)^2} = r \]\)

Squaring both sides:

\(\[ (a - 1)^2 + (b - p)^2 = r^2 \]\)

To find \(\( p \)\), we need the equation of the circle, but since we don’t have it, the above relationship is the best general result we can obtain. If specific values for \(\( a, b, r \)\) were provided, we could solve for \(\( p \)\).

### 4.1.3 Determine the equation of the tangent to the circle at \(\( N \)\).

The tangent line to a circle at a point \(\( (x_1, y_1) \)\) on the circle \(\( (x - a)^2 + (y - b)^2 = r^2 \)\) can be found using the formula:

\(\[ (x_1 - a)(x - a) + (y_1 - b)(y - b) = r^2 \]\)

For point \(\( N(1, p) \)\):

\(\[ (1 - a)(x - a) + (p - b)(y - b) = r^2 \]\)

Solving this for the tangent line in \(\( x \)\) and \(\( y \)\) terms, you will get the equation of the tangent line at \(\(N(1, p)\)\).

### Determine the values of k for which point A will be inside circle B.

The second circle is centered at \(\( B(4, 0) \)\) with equation \(\( (x - 4)^2 + y^2 = k^2 \)\).

For point \(\( A(a, b) \)\) to lie inside circle \(\( B \)\), the distance between \(\( A \)\) and \(\( B \)\) must be less than the radius \(\( k \)\) of circle \(\( B \)\):

\(\[ \sqrt{(a - 4)^2 + (b - 0)^2} < k \]\)

Squaring both sides:

\(\[ (a - 4)^2 + b^2 < k^2 \]\)

Thus, \(\( k \)\) must be greater than the distance between the centers of the circles \(\( A \)\) and \(\( B \)\):

\(\[ k > \sqrt{(a - 4)^2 + b^2} \]\)

In the general case, without specific coordinates for \(\( a \)\) and \(\( b \)\), this is the most precise form of the equation. If specific values for \(\( a \)\) and \(\( b \)\) were known, \(\( k \)\) could be explicitly calculated.

### Summary:

- The center of the circle \(\( A \)\) is given as \(\( (a, b) \)\) and radius \(\( r \)\).
- The value of \(\( p \)\) is determined by substituting \(\( N(1, p) \)\) into the circle's equation.
- The tangent to the circle at \(\( N \)\) can be derived from the general tangent equation provided.
- The value of \(\( k \)\) is determined by ensuring that the distance between circle \(\( A \)\) and \(\( B \)\) is less than \(\( k \)\).

Further solution refinement requires knowing the exact values for \(\( a, b, r \)\).