Sin17*cos43° =1/2*(sin(17° - 43°) +sin(17°+ 43°) =
1/2*(sin(17°- 43°) +sin60°) =1/2*(√3/2 - sin26°) =√3*/4 -sin26°/2 .
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√2*sinα -1 =√2*(sinα - 1/√2) =√2*(sinα - sin30°) =2√2sin(α-30°)/2*sin(α+30°)/2.