Answer:
∴Sum of interior angles in ΔABC = 180°
∠A + ∠B + ∠C = 180°
2x° + 4x° + 6x° = 180°
12x° = 180°
= x =
∴x = 15
∴∠C = (6)×(15)
= 90°
This means AC makes a 90° angle (i.e. ∠C) with BC.
∴AC is perpendicular to BC (Proved)
Also ΔABC is a right-angled triangle