Three-Dimensional-Geometry Question 432
Question: The projection of a line on a co-ordinate axes are 2, 3, 6. Then the length of the line is
[Orissa JEE 2002]
Options:
A) 7
B) 5
C) 1
D) 11
Show Answer
Answer:
Correct Answer: A
Solution:
Let d be the length of line, then projection on x-axis = dl = 2, projection on y-axis = dm = 3, Projection on z-axis = dn = 6 Now $ d^{2}(l^{2}+m^{2}+n^{2})=4+9+36 $
Þ $ d^{2}(1)=49 $
Þ $ d=7 $ .
BETA
