# Homework Help: Helping in plotting a graph

1. Sep 1, 2008

### ritwik06

How can I plot the graph for this:

a+b=c
and
$$b^{2}-4ac>0$$

2. Sep 1, 2008

### HallsofIvy

Re: Graph

What do you mean by a graph for that? I know how to graph functions of one or two variables. I see two equations, but not functions there. If you mean
c= f(a, b)= a+ b, then the graph is a plane containing the points (0, 0, 0), (1, 0, 1), and (0, 1, 1).

The graph of c= b2/4a is a much more complicated surface- it is basically as hyperboloid. The graph of all (a, b, c) such that b2- 4ac> 0 is the graph of all (a, b, c) such that c< b2/4a and consists of the points below the hyperboloid surface.

I doubt that's what you mean but I can't think what else the "graph" of two equations in 3 parameters could mean.

3. Sep 1, 2008

### ritwik06

Re: Graph

Actually the question is something of this sort:
If one of the angles of a triangle is 90 degree. The other angles be x and y.
If tan (x/2) and tan (y/2) be the roots of tghe equation:
ax^{2}+bx+c=0
find a relation between.
definately a+b=c
and discriminant>0
I wantd to plot the graphy of this out of curiosity and i ont understand a word you say:yuck:

4. Sep 1, 2008

### rocomath

Re: Graph

The reason you don't understand a single thing Halls said is bc you were too lazy to type up enough information for anybody to help you. If you want help, don't be lazy and use spellcheck.

5. Sep 1, 2008

### ritwik06

Re: Graph

I am sorry for that. My mother tongue ain't english but i'll try to do it again without the typo:
Actually the question is something of this sort:
If one of the angles of a triangle is 90 degree. The other angles be x and y.
If tan (x/2) and tan (y/2) be the roots of the equation:
$$ax^{2}+bx+c=0$$
find a relation between a,b,c.
definately a+b=c
and $$b^{2}-4ac>0$$
I wanted to plot the graph of this situation. Help me please~

I know that Halls was taking it to the #3 dimension. And thats what I dont want. I havent studied complex coordinate geomtry as yet.

6. Sep 1, 2008

### Defennder

Re: Graph

You want a graph of what again? What variables are used for the x and y axis? Halls didn't answer your question because you didn't state it properly.

7. Sep 1, 2008

### ritwik06

Re: Graph

No no, actually there are 3 parameters now, which vary and two conditions which they satisfy. I just want to know whether, the solution set of a,b,c can b represented graphically as was in the case such as y=x-3???