求下列各式的值.(1)sin45°•cos45°+tan60°•sin60°(2)sin30°-tan245°+34tan230°-cos60°.-数学

题目简介

求下列各式的值.(1)sin45°•cos45°+tan60°•sin60°(2)sin30°-tan245°+34tan230°-cos60°.-数学

题目详情

求下列各式的值.
(1)sin45°•cos45°+tan60°•sin60°
(2)sin30°-tan245°+
3
4
tan230°-cos60°
题型:解答题难度:中档来源:不详

答案

(1)原式=
2
2
×
2
2
+
3
×
3
2

=class="stub"1
2
+class="stub"3
2

=2;

(2)原式=class="stub"1
2
-12+class="stub"3
4
×(
3
3
)2-class="stub"1
2

=class="stub"1
2
-1+class="stub"1
4
-class="stub"1
2

=-class="stub"3
4

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