What is the relationship between angles in a 3D trigonometry problem?

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SUMMARY

The relationship between angles in a 3D trigonometry problem involves the angles a, b, and c, where angle c is separated from a 2D plane by angle b. The correct formula derived is tan(a) = sec(b) * tan(c), which accurately represents the projection of angle c onto the 2D plane as angle a. This formula was confirmed after initial incorrect attempts, emphasizing the importance of verifying mathematical relationships in 3D geometry.

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  • Understanding of trigonometric functions, specifically tangent and secant.
  • Familiarity with 3D geometry concepts, including projections onto 2D planes.
  • Knowledge of cuboids and their properties in relation to angles.
  • Basic algebra skills for manipulating trigonometric equations.
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  • Study the derivation of trigonometric identities in 3D geometry.
  • Learn about the applications of secant and tangent functions in various fields.
  • Explore 3D vector projections and their mathematical implications.
  • Practice solving complex trigonometric equations involving multiple angles.
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Students studying trigonometry, mathematicians working with 3D geometry, and educators teaching advanced trigonometric concepts.

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Homework Statement


[PLAIN]http://img708.imageshack.us/img708/1344/trig.jpg
The angle c is separated from a 2d plane by angle b (perpendicular to the 2d plane). Angle a is angle c projected onto the 2d plane. What is a in terms of b and c?


Homework Equations





The Attempt at a Solution


I put the whole thing in a cuboid, used the lengths of the edges, and came to tan(a)=tan(b)tan(c). Can i just double check this with someone, because i don't trust my maths.
 
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It doesn't work. When b = 0, no matter what c is, your equation gives a = 0, which doesn't make sense as a = c when b = 0.

This seems more appropriate to me: tan a = tan c / cos b
 
Yeah, it doesn't work, i probably should have checked some figures. I re-did it and i think i missed a 1. I got tan a = sqrt((tan b)^2 + 1) * tan c

=> tan a = sec b * tan c

so yes, youre completely right, thanks.
 

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