sin²30°+cos²30°+√8tan45°-6sin45°+﹙-1﹚²º¹²
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/27 16:22:13
![sin²30°+cos²30°+√8tan45°-6sin45°+﹙-1﹚²º¹²](/uploads/image/z/2522638-46-8.jpg?t=sin%26%23178%3B30%C2%B0%2Bcos%26%23178%3B30%C2%B0%2B%E2%88%9A8tan45%C2%B0%EF%BC%8D6sin45%C2%B0%EF%BC%8B%EF%B9%99-1%EF%B9%9A%26%23178%3B%26%23186%3B%26%23185%3B%26%23178%3B)
sin²30°+cos²30°+√8tan45°-6sin45°+﹙-1﹚²º¹²
sin²30°+cos²30°+√8tan45°-6sin45°+﹙-1﹚²º¹²
sin²30°+cos²30°+√8tan45°-6sin45°+﹙-1﹚²º¹²
sin²30°+cos²30°+√8tan45°-6sin45°+﹙-1﹚²º¹²
=(sin²30°+cos²30°)+√8tan45°-6sin45°+﹙-1﹚²º¹²
=1+2√2*1-6*√2/2+1
=1+2√2-3√2+1
=2-√2
2-根号2
最前面那楼正解!
因为sin^2 x+cos^2x=1
tan 45=1
sin45=根号2/2
(-1)^偶数次=1
所以
原式
=(sin²30°+cos²30°)+√8*1-6*根号2/2+1
=1+2根号2-3根号2+1
=2-根号2