问题
解答题
计算或化简: (1)sin45°•cos60°-cos45°•sin30°; (2)5tan30°-2(cos60°-sin60°); (3)(
(4)
|
答案
(1)原式=
×2 2
-1 2
×2 2
=0;1 2
(2)原式=5×
-2(3 3
-1 2
)3 2
=
-2×5 3 3 1- 3 2
=
-1+5 3 3 3
=
;8
-33 3
(3)原式=(
×3 2
)2005•(23 3
×2
)20042 2
=(
)2005•(2)2004=(1 2
)2004•22004•1 2 1 2
=
;1 2
(4)原式=
(2×2
-1)-(2 2
+3
)0-(2×1 2
-1)-12 2
=2-
-1-2 1
-12
=1-
-(2
+1)2
=-2
.2