Answer:
C) 405.3 ft
Step-by-step explanation:
A triangle is a polygon with three angles and three sides. Types of triangle are scalene, isosceles, equilateral, right angled triangle.
Given a triangle with angles A, B, C and the corresponding sides directly opposite to the angles as a, b, c. The sine rule states that:

In the triangle formed by point C, ship B and ship A, we have ∠A = 82°, ∠B = 78°, c = AB = 140 ft. Hence:
∠A + ∠B + ∠C = 180° (sum of angles in a triangle)
82 + 78 + ∠C = 180
∠C + 160 = 180
∠C = 20°
Using sine rule:

a = distance from Ship B to the signal fire at point C