Answer:
square; 60; 225.
Step-by-step explanation:
1) using the vectors rules to calculate the lengths of the sides AB; BC; CD and AD. When AB=BC=CD=AD it means, the shape is a square of rhombus.
2) using the vectors rules to calculate the lengths of the diagonales AC and BD. When AC=BD it means, the shape is a square.
3) The perimeter of the square ABCD is 15*4=60.
4) The area of the square ABCD is 15*15=225.
All the details are in the attached picture; answers are marked with colour.