问题 解答题
计算:
(1)
cos60°-tan45°
tan60°-2tan45°

(2)2cos30°-2sin30°+5tan60°;
(3)
1
2
sin60°+
2
2
cos45°+sin30°cos30°

(4)tan230°+2sin60°cos45°+tan45°-tan30°-cos230°.
答案

(1)原式=

1
2
-1
3
-2

=

2+
3
2

(2)原式=2×

3
2
-2×
1
2
+5
3

=6

3
-1;

(3)原式=

3
4
+
1
2
+
3
4

=

3
+1
2

(4)原式=

1
3
+
3
×
2
2
+1-
3
3
-
3
4

=

6
6
-4
3
+7
12

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