SOLUTION: If tan α = 9 and α is acute, find the exact value of sin 2α.

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Question 768669: If tan α = 9 and α is acute, find the exact value of sin 2α.
Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
we use a for alpha...

tan(a)=sin(a)/cos(a)=9
and
tan(a)=9=9/1
and thus y=9 , x=1, r=sqrt(82)
so that
sin 2a =
2sin(a)*cos(a)=
2(y/r)(x/r)=
2(9)(1)/82=9/41