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Mathematics
Mathematics
Problem
If
sin
A
=
k
\sin A = k
sin
A
=
k
for an acute angle
A
A
A
, which of the following correctly expresses
cos
A
\cos A
cos
A
in terms of
k
k
k
? a)
1
−
k
2
1-k^{2}
1
−
k
2
b)
1
−
k
\sqrt{1-k}
1
−
k
c)
1
−
k
2
\sqrt{1-k^{2}}
1
−
k
2
d)
1
+
k
2
\sqrt{1+k^{2}}
1
+
k
2
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