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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.
3
4

B.
3
8

C.
1
8

D.
1
4


3
4

B.
3
8

C.
1
8

D.
1
4
3
4
3
3
3
3
344
3
8

C.
1
8

D.
1
4
3
8
3
3
3
3
388
1
8

D.
1
4
1
8
1188
1
4
1
4
1144
▼优质解答
答案和解析
∵sin15°cos30°sin75°
=sin15°cos15°cos30°
=
1
2
sin30°cos30°
=
1
4
sin60°
=
1
4
×
3
2

=
3
8

故选B.
1
2
111222sin30°cos30°
=
1
4
sin60°
=
1
4
×
3
2

=
3
8

故选B.
1
4
111444sin60°
=
1
4
×
3
2

=
3
8

故选B.
1
4
111444×
3
2

=
3
8

故选B.
3
2
3
3
3
3
33222
=
3
8

故选B.
3
8
3
3
3
3
33888.
故选B.