sin（30°+α）+cos（60°+α）=sin30cosα+cos30sinα+cos60cosα-sin60sinα=cosα
sin（α+β）sin（α-β）=sin²αcos²β-cos²αsin²β
=sin²αcos²β+sin²αsin²β-sin²αsin²β-cos²αsin²β
=sin²α-sin²β
cos（α+β）cos（α-β）=cos²αcos²β-sin²αsin²β
=cos²αcos²β+cos²αsin²β-cos²αsin²β-sin²αsin²β
=cos²β-sin²α