计算下列各式的值.(1)2sin30°+3tan30°+cos45°tan60°(2)cos245°+cos30°•tan45°+sin260°.-数学

题目简介

计算下列各式的值.(1)2sin30°+3tan30°+cos45°tan60°(2)cos245°+cos30°•tan45°+sin260°.-数学

题目详情

计算下列各式的值.
(1)2sin30°+3tan30°+
cos45°
tan60°

(2)cos2 45°+cos30°•tan45°+sin2 60°.
题型:解答题难度:中档来源:不详

答案

(1)2sin30°+3tan30°+class="stub"cos45°
tan60°

=2×class="stub"1
2
+3×
3
3
+
2
2
3

=1+
3
+
6
6


(2)cos2 45°+cos30°•tan45°+sin2 60°
=(
2
2
)2+
3
2
×1+(
3
2
)2
=class="stub"1
2
+
3
2
+class="stub"3
4

=class="stub"5
4
+
3
2

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