1.cos30°-sin45°/sin60°-cos45° 2.(sin30^2)30°+2sin60°+tha45°-tan60°+(cos^2)30°3.√1-2tan60°+(tan^2)60° -tan60°（过程最重要）,为了测量山坡的护坡石坝与地面的倾斜角α,把一根长为4.5m的竹竿AC斜靠在石坝旁,量出竹竿长1m时它离地面的高度为0.6m,又量得竿顶与坝脚的距离BC=2.8m.这样∠α求就可以算出来了.求∠α

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1.（cos30°-sin45°）/（sin60°-cos45°）
=（√3/2-√2/2）/（√3/2-√2/2）
=1
2.(sin^2)30°+2sin60°+tha45°-tan60°+(cos^2)30°
=1/2^2+2√3/2+1-√3+（√3/2）^2
=1/4+√3+1-√3+3/4
=2
3.√【1-2tan60°+(tan^2)60° 】 -tan60°
=√【1-2√3+√3^2】-√3
=√【1-2√3+3】-√3
=√【4-2√3】-√3
=√3-1-√3
=-1

1.cos30°-sin45°/sin60°-cos45°
=[（½√3）-（½√2）]/[（½√3）-（½√2）]
=1
2.(sin30^2)30°+2sin60°+tha45°-tan60°+(cos^2)30°
=（½）²+2×（½√3）+1-（√3）+（½√3）²
=（¼）+（√3）+1-（√3）+（¾）
=2
3.√1-2tan60°+(tan^2)60° -tan60°
=[√（1-tan60°)²]-√3
=(√3)－1-√3
=-1

1.cos30°-sin45°/sin60°-cos45°
=(cos30°-cos45°)/(cos(90°-60°)-cos45°)
=(cos30°-cos45°)/(cos30°-cos45°)
=1;
2.(sin30^2)30°+2sin60°+tha45°-tan60°+(cos^2)30°
=sin²30°+cos²30°+2sin60°+tan45°-tan60°
=1+2*(√3/2)+1-√3
=2;
3.√1-2tan60°+(tan^2)60° -tan60°
=√(tan60°-1)²-tan60°
=tan60°-1-tan60°
=-1;