# ....question...

• Jan 12th 2008, 02:43 PM
Morzilla
....question...
I hope and pray that this thread does not get neg feedback....

Ok I am trying to find the area of three points;

A=(-2,5) B=(1,3) C=(-1,0)

I am following the text books examples on how to do this and so far it's working out. BUT in the text/example it talks about the "right angle is at vertex B."

MY question is (to understand this); what does the word vertex mean?

• Jan 12th 2008, 02:53 PM
Jhevon
Quote:

Originally Posted by Morzilla
I hope and pray that this thread does not get neg feedback....

Ok I am trying to find the area of three points;

A=(-2,5) B=(1,3) C=(-1,0)

I am following the text books examples on how to do this and so far it's working out. BUT in the text/example it talks about the "right angle is at vertex B."

MY question is (to understand this); what does the word vertex mean?

here, each of the points is a vertex of a triangle that is obtained by connecting all the points. you can think of a vertex here as a sharp or pointed edge of a figure. see here for more info
• Jan 12th 2008, 07:12 PM
mr fantastic
Quote:

Originally Posted by Morzilla
I hope and pray that this thread does not get neg feedback....

Ok I am trying to find the area of three points;

A=(-2,5) B=(1,3) C=(-1,0)
[snip]

Since the area of a single point is zero, the area of three three points will be (3)(0) = 0 ;)

Quote:

Originally Posted by Morzilla
I hope and pray that this thread does not get neg feedback....

Ok I am trying to find the area of three points;

A=(-2,5) B=(1,3) C=(-1,0)

I am following the text books examples on how to do this and so far it's working out. BUT in the text/example it talks about the "right angle is at vertex B."

MY question is (to understand this); what does the word vertex mean?

Do you understand why the angle at B is a right angle?

What will you do when the triangle you get by connecting three points does NOT contain a right angle?
• Jan 13th 2008, 04:54 AM
Morzilla
Quote:

Originally Posted by mr fantastic
Since the area of a single point is zero, the area of three three points will be (3)(0) = 0 ;)

Do you understand why the angle at B is a right angle?

What will you do when the triangle you get by connecting three points does NOT contain a right angle?

..no, sorry I don't understand, and the book doesn't explain either. uhmmmm I have no idea, this is the first time I ever see anything like this. Sorry for such inconvenience, and much thanks!!!

(Handshake)
• Jan 13th 2008, 05:10 AM
mr fantastic
Quote:

Originally Posted by Morzilla
..no, sorry I don't understand, and the book doesn't explain either. uhmmmm I have no idea, this is the first time I ever see anything like this. Sorry for such inconvenience, and much thanks!!!

(Handshake)

Are you familiar with the fact that if the product of the gradients of two line segments is equal to -1, then the line segments are perpendicular to each other? If so, calculate the gradient of line segments AB and CB. Now take the product of these two gradients ......
• Jan 13th 2008, 05:29 AM
Morzilla
Quote:

Originally Posted by mr fantastic
Are you familiar with the fact that if the product of the gradients of two line segments is equal to -1, then the line segments are perpendicular to each other? If so, calculate the gradient of line segments AB and CB. Now take the product of these two gradients ......

I used the given formula to calculate AB and CB

$\displaystyle [d(A,B)]^2+[d(B,C)]^2=[d(A,C)]^2$

and after I was asked to find the area. I got $\displaystyle \frac{13}{2}$...don't know if this is right or not...
• Jan 13th 2008, 11:43 AM
mr fantastic
Quote:

Originally Posted by mr fantastic
Are you familiar with the fact that if the product of the gradients of two line segments is equal to -1, then the line segments are perpendicular to each other? If so, calculate the gradient of line segments AB and CB. Now take the product of these two gradients ......

This is telling you how to show that the angle at B is 90 degrees .....
• Jan 14th 2008, 05:49 PM
Morzilla
Quote:

Originally Posted by mr fantastic
This is telling you how to show that the angle at B is 90 degrees .....

ahhhhhhh ok, ok THANKS!! :)

(Handshake)