NDA 2020 Mathematics question
If a line has direction ratios , then what is the sum of the squares of its direction cosines?
Answer: (D)
Solution
Whatever the direction ratios, the direction cosines of any line satisfy . Hence the sum is 1.
If a line has direction ratios , then what is the sum of the squares of its direction cosines?
Whatever the direction ratios, the direction cosines of any line satisfy . Hence the sum is 1.