求证:1+sina+cosa/1+sina-cosa+1-cosa+sina/1+cosa+sina=2/sina
问题描述:
求证:1+sina+cosa/1+sina-cosa+1-cosa+sina/1+cosa+sina=2/sina
答
1+sina+cosa/1+sina-cosa+1-cosa+sina/1+cosa+sina=[(1+sina+cosa)²+(1+sina-cosa)²]/[(1+sina)²-cos²a]=(1+sin²a+cos²a+2sina+2cosa+2sinacosa+1+sin²a+cos²a+2sina-2cosa...