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sin15°cos30°sin75°的值等于()A.34B.38C.18D.14
题目详情
sin15°cos30°sin75°的值等于( )
A.
B.
C.
D.
B.
C.
D.
3 3 4 4
C.
D.
3 3 8 8
D.
1 1 8 8
1 1 4 4
A.
| ||
4 |
B.
| ||
8 |
C.
1 |
8 |
D.
1 |
4 |
| ||
4 |
B.
| ||
8 |
C.
1 |
8 |
D.
1 |
4 |
| ||
4 |
3 |
3 |
3 |
| ||
8 |
C.
1 |
8 |
D.
1 |
4 |
| ||
8 |
3 |
3 |
3 |
1 |
8 |
D.
1 |
4 |
1 |
8 |
1 |
4 |
1 |
4 |
▼优质解答
答案和解析
∵sin15°cos30°sin75°
=sin15°cos15°cos30°
=
sin30°cos30°
=
sin60°
=
×
=
.
故选B.
1 1 12 2 2sin30°cos30°
=
sin60°
=
×
=
.
故选B.
1 1 14 4 4sin60°
=
×
=
.
故选B.
1 1 14 4 4×
=
.
故选B.
3 3 32 2 2
=
.
故选B.
3 3 38 8 8.
故选B.
=sin15°cos15°cos30°
=
1 |
2 |
=
1 |
4 |
=
1 |
4 |
| ||
2 |
=
| ||
8 |
故选B.
1 |
2 |
=
1 |
4 |
=
1 |
4 |
| ||
2 |
=
| ||
8 |
故选B.
1 |
4 |
=
1 |
4 |
| ||
2 |
=
| ||
8 |
故选B.
1 |
4 |
| ||
2 |
=
| ||
8 |
故选B.
| ||
2 |
3 |
3 |
3 |
=
| ||
8 |
故选B.
| ||
8 |
3 |
3 |
3 |
故选B.
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