# Find point on rhombus

1. Nov 11, 2014

### desmond iking

1. The problem statement, all variables and given/known data

A(7.0 ) , B(p,q) , C(1,2 ) and D (2.-5) are vertices of rhombus ABCD. determine p and q ,

i use the method of midpoint of AC and BD to find the ans, suprisingly , i gt the ans..

my question is , what rule to follow when it co mes to finding the vertices of rhombus? the ans is p=6 , q=7

BUT when i sketch it on diagram , it doesnt make sense. can someone help me on this
2. Relevant equations

3. The attempt at a solution

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2. Nov 11, 2014

### Staff: Mentor

A rhombus is a parallelogram with sides of the same length. A square is an example of a rhombus.

In your diagram, you placed the B point in the wrong place it should be higher and more to the right to make the sides parallel.

EDIT I must have fallen asleep whenI said it was a parallelogram with parallel sides duh...

Last edited: Nov 11, 2014
3. Nov 11, 2014

### SteamKing

Staff Emeritus
It helps here to know what the definition of a 'rhombus' is:

http://en.wikipedia.org/wiki/Rhombus

It's a quadrilateral with all four sides having the same length.

4. Nov 12, 2014

### Joffan

A square is a rather specialized example of a rhombus, when you specify a right-angled corner. But true. More useful here is the parallelogram status, because we already have the opposite sides (CD and DA) available to us, so we just need to apply those to get AB or BC (using the other one as a check).

In the diagram, B and D are both in the wrong quadrants, not just slightly shifted. C could do with better positioning too.

5. Nov 14, 2014

### ehild

Usually the vertexes of a polygon are numbered in a way that B is next to A anticlockwise and so on. See picture.
As the sides of the rhombus are parallel the vector drawn from A to B is the same as the vector drown form D to C.