Question

The diagonals in this quadrilateral are 5x-15 and 3x+9. For what value of x is the

quadrilateral a rectangle?

Answer 1

x = 12

Explanation:

The diagonals of a rectangle are congruent, thus

5x - 15 = 3x + 9 ( subtract 3x from both sides )

2x - 15 = 9 ( add 15 to both sides )

2x = 24 ( divide both sides by 2 )

x = 12