Four coordinates A, B, C and D form a rectangle. A = (2,8), B = (9, 2) and C'=(2, 2)
What are the coordinates of D?​

What is the multiple zero and multiplicity of f(x) = (x ? 3)(x ? 3)(x + 5)? multiple zero is 3; multiplicity is 2 multiple zero is 5; multiplicity is 1 multiple zero is ? 5; multiplicity is 1 multiple zero is ? 3; multiplicity is 2

Which one ? is the answer and how to find this answer

Find the area of the regular hexagon if a side is 20 cm.