Trigonometry--The derivation of Sin 18° www.andrews.edu/~calkins/math/webtexts/NUMB18.HTM www.andrews.edu/~calkins/math/webtexts/NUMB18.HTM Trigonometry--The derivation of Sin 18° Trigonometry--The derivation of Sin 18° www.andrews.edu/~calkins/math/webtexts/NUMB18.HTM Trigonometry--The derivation of Sin 18°