Geometry help

rachelmaddie said:
So find the midpoint of AB using the midpoint formula then substitute to find the point on the line segment?
Click to expand...
Post #11 contains 2 examples (midpoint and 2/3) and a solution for your case. Did you read it? Do you understand it?
 
Subhotosh Khan said:
What does response #11 say?
Click to expand...
Find the midpoint of AB first using the midpoint formula.
Midpoint = (x1 + x2/2, y1 + y2/2)
A(3, -5)
B(13, -15)
Average x-value = (3 + 13)/2 = 8
Average y-value = (-5 + -15)/2 = -10
Midpoint is (8, -10)
Let P = point which is 4/5 of the way from A to B
P = (3 + 4/5 x 10, -5 + 4/5 x -10)
= (3 + 8, - 5 - 8)
= (11, -13)

Is this correct?
 
rachelmaddie said:
Find the midpoint of AB first using the midpoint formula.
Midpoint = (x1 + x2/2, y1 + y2/2)
A(3, -5)
B(13, -15)
Average x-value = (3 + 13)/2 = 8
Average y-value = (-5 + -15)/2 = -10
Midpoint is (8, -10)
Let P = point which is 4/5 of the way from A to B
P = (3 + 4/5 x 10, -5 + 4/5 x -10)
= (3 + 8, - 5 - 8)
= (11, -13)

Is this correct?
Click to expand...
Why are you combining the midpoint example and the original problem?
 
rachelmaddie said:
Find the midpoint of AB first using the midpoint formula.
Midpoint = (x1 + x2/2, y1 + y2/2)
A(3, -5)
B(13, -15)
Average x-value = (3 + 13)/2 = 8
Average y-value = (-5 + -15)/2 = -10
Midpoint is (8, -10)
Let P = point which is 4/5 of the way from A to B
P = (3 + 4/5 x 10, -5 + 4/5 x -10)
= (3 + 8, - 5 - 8)
= (11, -13)

Is this correct?
Click to expand...
Check with response #11 - what do you find?
 
rachelmaddie said:
Find the length between the two points first using the distance formula.
A(3, -5)
B(13, -15)
d^2 = (x2 - x1)^2 + (y2 - y1)^2
d^2 = (13 - 3)^2 + ((-15) - (-5))^2
d^2 = (10)^2 + (-10)^2
d^2 = 100 + 100
d^2 = 14.14

Is this right?
Click to expand...
\(\displaystyle 100 + 100\neq14.14\)
 
rachelmaddie said:
That is the original problem?
Click to expand...
Do you understand that the midpoint example and the original problem are different problems? Midpoint is 1/2 of the way from A to B. The point in your problem is 4/5 of the way from A to B. See the difference?
 
Rachelmaddie,
There is no need to find the length of AB or the midpoint of AB. It is clear that you do not understand what is going on.
Please go back to my post #9 and I can walk you through it. Have you drawn a diagram and labelled A, B and C?
 
Harry_the_cat said:
Rachelmaddie,
There is no need to find the length of AB or the midpoint of AB. It is clear that you do not understand what is going on.
Please go back to my post #9 and I can walk you through it. Have you drawn a diagram and labelled A, B and C?
Click to expand...
1)
A(3, -5)
B(13, -15)
XB - XA = 13 - 3 = 10
4/5 x 10 = 8
YB - YA = -15 - (-5) = -10
4/5 x -10 = -8
So XC - XA = 8 -> XC = 8 + XA = 8 + 3 = 11
YC - YA = (-8) - (-5) -> YC = -8 + (-5) = - 8 - 5 = -13
= (11, -13)
 
rachelmaddie said:
That is the original problem?
Click to expand...
Come on the original problem did not give you the midpoint nor did it tell you to find the midpoint. Please look at the work you posted in post #24 . Now you got (11,-13). Now look carefully at that post and see if you needed the part you wrote about midpoints to get (11, -13)
 
Jomo said:
Come on the original problem did not give you the midpoint nor did it tell you to find the midpoint. Please look at the work you posted in post #24 . Now you got (11,-13). Now look carefully at that post and see if you needed the part you wrote about midpoints to get (11, -13)
Click to expand...
I just made corrections. See post #36
 
The distance from 3 to 13 is 10. 4/5 of that is 10(4/5)= 8 so 4/5 of the way from 3 to 13 is 3+ 8= 11. The (signed) distance from -5 to -15 is -10. 4/5 of that is -10(4/5) is -8 so 4/5 of the way from -5 to -15 is -5+ (-15- (-5))(4/5)= -5 -5+ (-10)(4/5)= -5 -5- 8= -13. The point 4/5 of the way between (3, -5) to (13, -15) is (11, -13).
 
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