Highly selective Backlog Qs for JEE MainMathematicsStraight Lines
The area of a triangle is 5. If two of its vertices are 2 , 1 ,   3 , - 2 and the third vertex lies on the line y = x + 3 , then the third vertex is -
Options
- A- 7 2 , - 13 2
- B- 7 2 , 13 2
- C7 2 , - 13 2
- D7 2 , 13 2
Correct answer
D. 7 2 , 13 2
Step-by-step solution
Let the third vertex be h ,   k Since it lies on line y = x + 3 ∴   k = h + 3 ........(1) Also area of triangle is 5 ∴ 1 2 2 - 2 - k + 3 k - 1 + h   1 + 2 = ±   5 ⇒ k + 3 h -   7 = ±   10 ........(2) Solving (1) & (2) we get h = 7 2 ,   k   = 13 2 ⇒   7 2 , 13 2 and h = - 3 2 ,   k = 3 2 ⇒   - 3 2 , 3 2