问题 填空题
已知在△ABC,∠C=90°,a:b=
3
,则sinA=______,cosA=______,tgA=______,ctgA=______.
答案

∵设Rt△ABC中a=

3
x,则b=x,c=
a2+b2
=
(
3
x)
2
+x2
=2x,

∴a:b:c=

3
:1:2,

∴sinA=

a
c
=
3
2
,cosA=
b
c
=
1
2
,tgA=
a
b
=
3
,ctgA=
b
a
=
3
3

故答案为:

3
2
1
2
3
3
3

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