The diagonals of a rectangle also have a special property.
Theorem
If a parallelogram is a rectangle, then its diagonals are congruent.
If …
ABCD is a rectangle
Then …
You will prove Theorem 6-15 in Exercise 41.
Multiple Choice In rectangle RSBF, SF = 2x + 15 and
How can you find the length of a diagonal?
Since RSBF is a rectangle and its diagonals are congruent, use the expressions to write an equation.
Think | Write |
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You know that the diagonals of a rectangle are congruent, so their lengths are equal. | SF = RB |
Set the algebraic expressions for SF and RB equal to each other and find the value of x. |
|
Substitute 9 for x in the expression for RB. |
The correct answer is D. |
Reasoning What type of triangle is