Answer:
Gregoire is correct; the diameter is a chord that passes through the center of the sphere.
Step-by-step explanation:
A sphere is a geometrical shape formed from a circle. Some of its parts are: diameter, center, radius circumference, etc.
The center of a sphere is a point at its middle. The diameter is a straight line, e.g a chord, that is drawn from one point on the circumference of a sphere to another point and passes through its center. While radius is a line that is from the center of the sphere to a point on its circumference.
A diameter is twice of a radius, so that:
Radius = 
⇒ Diameter = 2 × Radius
Therefore with respect to the question, Gregoire is correct because a diameter is a chord that passes through the center of the sphere.
R+s-t-(r-s+t)
=2s-t is the answer
People think this answer would be just =2s but I have verified with an online calculator and the answer that textbooks look for regarding this is 2s-t
You would assume you would go r-r and thats 0 so no r's
you would say s-(-s) makes it plus and theres 2s
and you would say -t -(+t) is -t
that's why the answer is 2s-t
At first I also did t-(+t) and thought it would be no t's but the answer is in fact 2s-t
Is there supposed to be a photo?
Answer:
Step-by-step explanation:

1) -(5.8x14) = -406/5 = -81.2
2) (-1/3)(-1) = 1/3 = 0.3333333....
3) -2 + 1/4 / 1 + 1/2
-7/4 / 3/2
-1.75 / 1.5 = -7/6 = -1.166....7
What do you mean by “and”?????
Is it divided or add??
I’m only sure about the first one but tell me what and mean