题目内容
已知tana=3,求下列各式的值.
(1)
;
(2)sin2a+11cos2a.
(1)
| 3sina-cosa |
| sina+5cosa |
(2)sin2a+11cos2a.
由tana=3,
(1)则
=
=
=1;
(2)则sin2a+11cos2a=
=
=
=2.
(1)则
| 3sina-cosa |
| sina+5cosa |
| 3tanα-1 |
| tanα+5 |
| 9-1 |
| 3+5 |
(2)则sin2a+11cos2a=
| sin2α+11cos2α |
| sin2α+cos2α |
| tan2α+11 |
| tan2α+1 |
| 9+11 |
| 9+1 |
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