The foci of the ellipse 4x² + 9y² = 1 are at Q and R. If P(x, y) is any point on the ellipse, then what is PQ + PR equal to?

If P(2, 4), Q(8, 12), R(10, 14) and S(x, y) are vertices of a parallelogram, then what is (x + y) equal to?  

The equation of a circle is 

(x² - 4x + 3) + (y² - 6y + 8) = 0

Which of the following statements are correct?

I. The end points of a diameter of the circle are at (1, 2) and (3, 4).

II. The end points of a diameter of the circle are at (1, 4) and (3, 2).

III. The end points of a diameter of the circle are at (2, 4) and (4, 2).

Select the answer using the code given below.

Consider the points P(4k, 4k) and Q(4k, -4k) lying on the parabola y² = 4kx. If the vertex is A, then what is ∠PAQ equal to?