Answer:
The diagonals of a rhombus are always perpendicular.
Explanation:
We have been given an incomplete sentence. We are supposed to fill in the given blank.
Given sentence:
The diagonals of a rhombus are _____perpendicular.
We know that rhombus is a parallelogram. One of properties of rhombus is that the diagonals of rhombus always bisect each other at right angles.
Since diagonals of rhombus are always perpendicular, therefore, the missing word from our given sentence is 'always'.