SOLUTION: Points A, B and C are collinear. Point B is the midpoint of the line segment AC. Point D is a point not collinear with the other points for which DA=DB and DB=BC=10. Then DC is: A

Algebra ->  College  -> Linear Algebra -> SOLUTION: Points A, B and C are collinear. Point B is the midpoint of the line segment AC. Point D is a point not collinear with the other points for which DA=DB and DB=BC=10. Then DC is: A      Log On


   



Question 1044204: Points A, B and C are collinear. Point B is the midpoint of the line segment AC. Point D is a point not collinear with the other points for which DA=DB and DB=BC=10. Then DC is:
A) 20/✔️3
B) 10✔️2
C) 10✔️3
D) 20
E) 40/✔️3

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Let y = distance of point D from segment AB.
Then 5%5E2%2B+y%5E2+=+10%5E2.
===> y%5E2+=+10%5E2+-+5%5E2
But also the distance of the foot of the perpendicular bisector of AB from point C is 5+10 = 15 units. Hence,
15%5E2+%2B+y%5E2+=+%28DC%29%5E2
===> 15%5E2+%2B+10%5E2+-+5%5E2+=+%28DC%29%5E2 ===> %28DC%29%5E2+=+300
===> DC+=+10sqrt%283%29.