In right angle triangle at B, if tan A=1,then verify that 2 sin A cos A=1.
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Answer:
In △ABC, ∠ABC=90
o
∴tanA=
AB
BC
Since tanA=1 (Given)
AB
BC
=1 ∴BC=AB
Let AB=BC=k, where k is a positive number.
Now, AC
2
=AB
2
+BC
2
∴AC=
AB
2
+BC
2
=
k
2
+k
2
∴AC=k
2
∴sinA=
AC
BC
=
k
2
k
=
2
1
,cosA=
AC
AB
=
k
2
k
=
2
1
2sinAcosA=2(
2
1
)(
2
1
)=1
∴2sinAcosA=1
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