In quadrilateral ABCD AB=5, BC =8, and CD = 20 units angle B and C both right angles . what is length of segment AD ?

answer was 17 units how ? my answer was different how ?

sri

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- Apr 3rd 2008, 01:36 PMsri340geometry help
In quadrilateral ABCD AB=5, BC =8, and CD = 20 units angle B and C both right angles . what is length of segment AD ?

answer was 17 units how ? my answer was different how ?

sri - Apr 3rd 2008, 01:49 PMMoo
Hello,

Let E (on [DC]) be the point such as ABCE is a rectangle.

Its dimensions are 8x20

So you have DE=DC-EC=20-5=15

AE=BC=8

ADE is a rectangle triangle in E, so you can use the Pythagorean theorem and have AD - Apr 7th 2008, 02:34 PMveronica marswhat did u get??
i thought i was doing it right, but i got 20.61552813

- Apr 7th 2008, 06:57 PMSoroban
Hello, sri340!

Quote:

In quadrilateral $\displaystyle ABCD\!:\;\;AB=5,\;BC=8,\;CD = 20.$

$\displaystyle \angle B \,=\,\angle C \,=\,90^o$

What is length of segment $\displaystyle AD$ ?

Answer was 17 units.

My answer was different . . . how ?

It's hard to see your work from here . . .

. . But it looks like you played the $\displaystyle {\color{blue}J\heartsuit}$ instead of the $\displaystyle {\color{blue}3\clubsuit}$

Code:`A 5 B`

* - - - *

* : |

* : |

* :8 |8

* : |

* : |

D * - - - - - + - - - * C

: 15 E 5 :

: - - - - 20 - - - :

In right triangle $\displaystyle AED$, use Pythagorus:

. . . $\displaystyle AD^2 \;=\;DE^2 + AE^2$