Answer:
The height of the spire must be 69.24 m
Step-by-step explanation:
The information given are;
The initial angle of elevation of the tip of the spire from the tip of the shadow = 25°
The angle of elevation of the tip of the spire from the tip of the shadow after moving 100 m closer = 55°
The change distance moved closer to the church spire = 100 m
Let the base angles of the triangle formed by the two rays of the tip of the spire to the tip of the shadow be 25° and ∠x°
We have;
∠x° and the 55° angle of the ray from the tip of the spire to the tip of the shadow are supplementary angles (angle on a straight line)
Therefore;
∠x° = 180° - 55° = 125°
The calculated angle 125° above, the given 25° and the angle in between the two rays from the tip of the spire to the tip of the shadows are the interior angles of the triangle formed by the two rays of the tip of the spire to the tip of the shadow
Let the angle in between the two rays from the tip of the spire to the tip of the shadows = y
Therefore;
125° + y° + 25° = 180 (Angle sum theorem)
y° = 180° - (125° + 25°) = 30°
By sin rule, we have;
100/(sin (30°)) = (The length of the initial ray from the tip of the spire to the tip of the shadow before the shift)/(sin(125°))
Let the length of the initial ray from the tip of the spire to the tip of the shadow before the shift = l
100/(sin (30°)) = l/(sin(125°))
l = (sin(125°))×100/(sin (30°)) = 163.83 m
The height of the spire, by trigonometric ratio = sin(25°) × 163.83 m = 69.24 m
The height of the spire = 69.24 m.
