SOLUTION: Please solve equation without using a calculator. Show all work {{Cos(2sin^-1(1/4)}}

Question 683117: Please solve equation without using a calculator. Show all work
{{Cos(2sin^-1(1/4)}}
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
Please solve equation without using a calculator. Show all work
{{Cos(2sin^-1(1/4)}}
sin^-1(1/4)=an angle x whose sin=1/4
Cos(2sin^-1(1/4)=cos2x
=1-2sin^2x=1-2*(1/4)^2
=1-(2/16)
=1-(1/8)
=7/8
check with calculator:
2sin^-1(1/4)≈.2527*2≈.5054
cos(.5054)≈.875=7/8
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