How are the opposite angles of a parallelogram related?

We can try to draw a picture keeping the adjuscent sides unequal as said in the question.

What do we know about the opposite angles of a parallelogram?

What do we know about the diagonals of a parallelogram?

Let us check each option one by one.

What do we know about the diagonals of a square?

What do we know about the opposite sides of a parallelogram?

Can we write the length of all the sides using an unknown variable say,x.

How are the opposite angles in a parallelogram related?

(iv) What do we know about the angles of a rectangle? Does it go with parallelograms as well?