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?

Direction: Consider the following for the items that follow:

A triangle ABC is inscribed in the circle x² + y² = 100. B and C have coordinates (6, 8) and (-8, 6) respectively.

What is BAC equal to?

Direction: Consider the following for the items that follow:

A triangle ABC is inscribed in the circle x² + y² = 100. B and C have coordinates (6, 8) and (-8, 6) respectively.

What are the coordinates of A? 

Direction: Consider the following for the items that follow:

ABCD is an isosceles trapezium and AB is parallel to DC. Let A(2, 3), B(4, 3), C(5, 1) be the vertices.

What are the coordinates of vertex D?