题目内容
在△ABC中,∠ACB=90°,cosA=
,AB=8cm,则△ABC的面积为______cm2.
| ||
3 |
∵在△ABC中,∠ACB=90°,AB=8cm,
cosA=
=
=
,
∴AC=
cm
∴BC=
=
(cm).
∴S△ABC=
AC×AB=
×
=
(cm2).
cosA=
AC |
AB |
AC |
8 |
| ||
3 |
∴AC=
8
| ||
3 |
∴BC=
82-(
|
8
| ||
3 |
∴S△ABC=
1 |
2 |
1 |
2 |
8
| ||
3 |
8
| ||
3 |
32
| ||
3 |
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