问题
解答题
计算下列各题. (1)sin230°+cos245°+
(2)
(3)tan2°tan4°•tan6°…tan88°. |
答案
(1)原式=(
)2+(1 2
)2+2 2
×2
×1,3 2
=
+1 4
+1 2
,6 2
=
+3 4
;6 2
(2)原式=
+(
)2+(3 2
)21 2
×3 3
,3
=
+1 3
;3
(3)原式=tan2°•tan4°•tan6°•cot6°•cot4°•cot2°,
=(tan2°•cot2°)(tan4°•cot4°)•(tan6°•cot6°),
=1