问题 解答题
计算:
(1)(1-sin60°+cos60°)(sin90°+cos60°-cos30°);
(2)
cos45°-sin30°
cos45°+sin30°
-
cos40°
sin50°
答案

(1)原式=(1-

3
2
+
1
2
)(1+
1
2
-
3
2
)=3-
3
2
3

(2)原式=

2
2
-
1
2
2
2
+
1
2
-1

=(

2
-1)2-1

=2-2

2

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