Class 12 Determinants · Short Answer2 Markstriangle_area
Class 12 Maths · Determinants · Short Answer #88
Using a determinant, find the equation of the line through (3,1) and (9,3).
✅ Step-by-Step Solution
Final Answer: x−3y=0
- A point (x,y) is collinear with (3,1),(9,3) exactly when \(\begin{vmatrix}x & y & 1\\3 & 1 & 1\\9 & 3 & 1\end{vmatrix}\)=0.
- Expand: x(1−3)−y(3−9)+(9−9)=−2x+6y=0.
- Therefore the line equation is x−3y=0.
📋 CBSE Stepwise Marking Scheme
- [0.5 marks] A point (x,y) is collinear with (3,1),(9,3) exactly when \(\begin{vmatrix}x & y & 1\\3 & 1 & 1\\9 & 3 & 1\end{vmatrix}\)=0.
- [1 mark] Expand: x(1−3)−y(3−9)+(9−9)=−2x+6y=0.
- [0.5 marks] Therefore the line equation is x−3y=0.
Master Chapter 4: Determinants
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