In 3‐dimensional space, a direction can be specified as follows. Take a point P such that has the given direction and |OP| = 1. Let α, β and γ be the three angles ∠xOP, ∠yOP and ∠zOP, measured in radians with 0 ≤ α, β, γ ≤ π. Then cosα, cosβ, and cosγ are the direction cosines of . Point P has coordinates (cosα, cosβ, cosγ), and so cos2α + cos2β + cos2γ = 1.
direction angles
- BAC
- Bachelard, Gaston (1884–1962)
- BACI design
- Bacillariophyceae
- Bacillariophyta
- bacillus
- back-arc basin
- back-arc spreading
- backbiting
- backbone
- backbone cabal
- backbone network
- back breeding
- back cross
- back donation
- back door
- backdoor
- back driving
- back electromotive force
- back e.m.f.
- back end
- back end database
- back end process
- back-end processor
- back end system