Let in a ABC, the length of the side AC be 6, the vertex B be (1,2,3) and the vertices A, C lie on the line x-63= y-72= z-7-2. Then the area (in sq. units) of ABC is:
- 42
- 17
- 56
- 21
Answer
(4) 21
Solution
A,C lie on the line, so the height from B is its distance from the line.
[figure]
P0(6,7,7), d=(3,2,-2), P0B=(-5,-5,-4)
P0B d=(18,-22,5) h= 833 17= 7 17 17=7
Area = 12 6 7=21
Answer: (4)