已知sin(a+135°)=5/13,cos(45°-β ),且-45°cos(45°-β )=3/5

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已知sin(a+135°)=5/13,cos(45°-β ),且-45°cos(45°-β )=3/5
已知sin(a+135°)=5/13,cos(45°-β ),且-45°
cos(45°-β )=3/5

已知sin(a+135°)=5/13,cos(45°-β ),且-45°cos(45°-β )=3/5
cos2(a-β)=2cos^2(a-β)-1
-45°