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True thickness from vertical thickness 150 m

Short answer

True thickness equals vertical thickness times cosine of dip: 150 m × cos(47°) = 102.3 m.

The vertical thickness of inclined bedrock limestone is 150 m and the true dip amount is 47°. Calculate the true thickness of the limestone bedrock.

Principle: the vertical thickness tvt_v is measured in a vertical hole; the true thickness tt is measured normal to the bedding. For a bed dipping at δ\delta:

t=tvcos⁡δt = t_v\cos\delta 
         |  tv
    _____|_____
    \    |    \     t = tv cos(dip)
     \___|_____\
          dip

Calculation

t=150cos⁡47∘=150×0.6820=102.30 m\begin{aligned} t &= 150\cos 47^\circ \\ &= 150 \times 0.6820 \\ &= 102.30\ \text{m} \end{aligned}

Answer: true thickness of the limestone = 102.3 m.

✓ Answer checked by Claude Opus 5.5 (high effort)

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