Is it possible to delete a post once it has been submitted?

[Alkatran]

Which statements are true?

A) A vector can have zero magnitude if one of its components is not zero.
B) If a + b = c and a2 + b2 = c2, then the angle between a and b is 90°.
C) Two vectors having different magnitudes can be combined to give a vector sum of zero.
D) The magnitude of the difference between two vectors can be greater than the magnitude of at least one of the vectors.
E) If a + b = c and a2 + b2 < c2, then the angle between a and b is between 0° and 90°.
F) Three vectors which do not lie in the same plane can never give a vector sum of zero.
G) If a + b = c and a + b = c, then the angle between a and b is 180°.

I've got: FTFTTTF

I just need some help translating what these questions mean
A: Components are the x,y,z components. Magnitude has to be > 0
B: Is it a length or a vector? I know that since they're perpendicular two vectors squared WILL equal...
C: Obviously if one is shorter than the other it can't undo the other completely
D: Opposite directions. True
E: I'm not sure. But I think this is true... unless than angle can be greater than 90?
F: True
G: In the question the first a + b = c is bold and the second is italics, that's the only difference between them. I highly doubt it change their meaning, other than that I think G is false.

 

[Alkatran]

Got it.

Why can't I delete the post?

 

[M98Ranger]

A) This statement is true. A vector can have a magnitude of zero if one of its components is zero, but it can also have a magnitude of zero if all its components are zero.
B) This statement is true. This is known as the Pythagorean theorem and applies to right triangles where the two shorter sides (a and b) are added together to equal the hypotenuse (c).
C) This statement is false. Two vectors with different magnitudes cannot cancel each other out completely.
D) This statement is true. The magnitude of the difference between two vectors can be greater than the magnitude of at least one of the vectors if they are in opposite directions.
E) This statement is true. The angle between a and b can only be between 0° and 90° if their magnitudes are smaller than the magnitude of c.
F) This statement is true. Three vectors that do not lie in the same plane cannot cancel each other out completely.
G) This statement is false. The angle between a and b can be 180° if they are in opposite directions and have the same magnitude.