Geometry

Question Analysis:
This question checks understanding of when a rhombus is also a square.
Focus is on the condition: equal diagonals.

Key Concept Explanation:
In a rhombus, diagonals are not usually equal, but they are in a square.

Step-by-Step Solution:
If AC = BD, then:
6x = 2x + 12
4x = 12
x = 3
But plug in to check:
AC = 18, BD = 18 → correct.

Common Mist...