Question

If area of triangle is 35 sq units with vertices (2, – 6), (5, 4) and (k, 4). Then find the value of k.

Answer 1

We have Area of triangle

⇒ |2 (4 − 4) + 6(5 − k) + 1(20 − 4k)| = 70 

⇒ 2 (4 − 4) + 6 (5 − k) + 1(20 − 4k) = ± 70 

⇒ 30 − 6k + 20 − 4k = ± 70 

On taking positive sign, − 10k + 50 = 70 

⇒ − 10k = 20 ⇒ k = − 2 

On taking negative sign, 

− 10k + 50 = − 70 

⇒ − 10k = − 120 ⇒ k = 12 

∴ k = 12, − 2 

Comments

Explanation is good