99 Percentile Qs Bank for JEE MainMathematicsDeterminants
If A , B , C are the angles of a triangle and 1 1 1 1 + sin A 1 + sin B 1 + sin C sin A + sin 2 A sin B + sin 2 B sin C + sin 2 C = 0, then triangle A B C is
Options
- Aright angled isosceles
- Bisosceles
- Cequilateral
- Dscalene
Correct answer
B. isosceles
Step-by-step solution
R 2 → R 2 - R 1 1 1 1 sin A sin B sin C sin A + sin 2 A sin B + sin 2 B sin C + sin 2 C R 3 → R 3 - R 2 = 1 1 1 sin A sin B sin C sin 2 A sin 2 B sin 2 C = sin A - sin B × sin B - sin C × sin C - sin A ⇒ Either A = B or B = C or C = A So Δ is isosceles