need help with finding slopes (quadrilateral w/ par. sides)

L

lala321

New member
Joined
Feb 8, 2009
Messages
6
Quadrilateral ABCD has two pairs of parallel sides,AB||CD and BC||DA.The coordinates of A are (1,2),the coordinates of B are (7,-1) the coordinates of C are (8,2) the coordinates of D are unknown

What is the slope of AB?

What is the slope of CD?

Write an equation for CD.

What is the slope of BC?

What is the slope of AD?

Write an equation for AD

Use the equation of CD and the equation of AD to find the coordinates of D
 
Re: need help with finding slopes

lala321 said:
Quadrilateral ABCD has two pairs of parallel sides,AB||CD and BC||DA.The coordinates of A are (1,2),the coordinates of B are (7,-1) the coordinates of C are (8,2) the coordinates of D are unknown

What is the slope of AB?

What is the slope of CD?

Write an equation for CD.

What is the slope of BC?

What is the slope of AD?

Write an equation for AD

Use the equation of CD and the equation of AD to find the coordinates of D
Click to expand...

Please show us your work, indicating exactly where you are stuck - so that we know where to begin to help you.

To start:

Plot the points approximately - and join those as instructed.

Find the slope of the lines.

for quick review go to:

http://www.purplemath.com/modules/slope.htm
 
Re: need help with finding slopes

I need you to answer the questions and explain how you got them.
 
Re: need help with finding slopes

lala321 said:
I need you to answer the questions and explain how you got them.
Click to expand...

I need you to show your work and explain where you are stuck.
 
Re: need help with finding slopes

Ok i understand how to find the slope of the first question but i dont know how to find the slope of CD because i dnt know the coordinates of D
 
lala321 said:
i dont know how to find the slope of CD because i dnt know the coordinates of D
Click to expand...
Use the fact that you have parallel opposite sides. Parallel lines have the same slope. :wink:

Eliz.
 
Re: need help with finding slopes

lala321 said:
Quadrilateral ABCD has two pairs of parallel sides,AB||CD and BC||DA.The coordinates of A are (1,2),the coordinates of B are (7,-1) the coordinates of C are (8,2) the coordinates of D are unknown

What is the slope of AB?

Assume that the co-ordinate of D is (x[sub:110jaqr8]1[/sub:110jaqr8],y[sub:110jaqr8]1[/sub:110jaqr8])

and then find expressions for slope of CD and DA. Equate those to slopes of AB and BC, respectively.


What is the slope of CD?

Write an equation for CD.

What is the slope of BC?

What is the slope of AD?

Write an equation for AD

Use the equation of CD and the equation of AD to find the coordinates of D
Click to expand...
 
Re: need help with finding slopes

The slope of AB is -2/5..where do i go from there
 
Re: need help with finding slopes

lala321 said:
The slope of AB is -2/5<<<This does not seem correct. Please show work.


..where do i go from there
Click to expand...


Find slope of BC

Assume that the co-ordinate of D is (x[sub:131b6lot]1[/sub:131b6lot],y[sub:131b6lot]1[/sub:131b6lot])

and then find expressions for slope of CD and DA. Equate those to slopes of AB and BC, respectively.

You'll have two equations with two unknowns.

Solve.
 
Re: need help with finding slopes

Sorry i made a mistake.The correct slope for AB is -3/6
 
Re: need help with finding slopes

lala321 said:
Sorry i made a mistake.The correct slope for AB is -3/6<<< Correct = - 1/2 ...Now continue..
Click to expand...
 
Re: need help with finding slopes

Sooooo lala deeda: how you sloping now?
 
You must log in or register to reply here.
Top