for this i tried squaring both sides which gave me sin^2 x = 2-1 = 1
which didn't work
then i tried going backwards with the cos equation
cos^2x = (1-sin^2 x) = a + b sqrt2
rearranged to get sin^2x = -a -b sqrt2 + 1
i didnt know what to do from here
please help thanks
sin x = sqrt (2) - 1
sin^2 x = [ sqrt (2) - 1 ] ^2 = [ sqrt (2) - 1 ] * [ sqrt (2) - 1 ] =
sqrt (2) *sqrt (2) - 1*sqrt(2) - 1*sqrt(2) + (-1)(-1) =
2 - 2sqrt (2) + 1 =
[ 3 - 2sqrt (2) ]
So.....using an identity.....
cos^2x = 1 - sin^2 x
And we have that
1 - [ 3 - 2sqrt(2) ] =
-2 + 2sqrt (2) .....so a = -2 and b = 2