Question

Sin3L(альфа)-sinL/cos3L-cosL=
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Answer 1

(Sin3L-sinL)/(cos3L-cosL)=
2sin(3L-L)/2·cos(3L+L)/2/-2sin(3L+L)/2·sin(3L-L)/2=
=-sinL·cos2L/sin2L·sinL=-ctg2L