问题 解答题
计算或化简:
(1)
3
cos30°+
2
sin45°;
(2)
tan45°-cos60°
sin60°
•tan 30°;
(3)(sin60°+cos 45°)(sin 60°-cos 45°);
(4)6tan230°-
3
sin 60°-2sin 45°.
答案

(1)原式=

3
×
3
2
+
2
×
2
2
=
3
2
+1=
5
2

(2)原式=

1-
1
2
3
2
×
3
3
=
1
2
×
2
3
×
3
3
=
1
3

(3)原式=sin260°-cos245°=(

3
2
2-(
2
2
2=
3
4
-
2
4
=
1
4

(4)原式=6×(

3
3
2-
3
×
3
2
-2×
2
2
=2-
3
2
-
2
=
1
2
-
2

不定项选择
单项选择题 B型题