Originally posted by Gasfene:
Copying from CoolMyth's solution:
sin 2x - cos x = 1
2 sin x cos x = 1 + cos x
Square both sides and let z = cos x [b](where z must be between -1
and 1 since it is a cosine curve)
4z^2 * (1 - z^2) = (1 + z)^2
Expand everything out:
4z^4 - 3z^2 + 2z + 1 = 0
(z + 1)(4z^3 - 4z^2 + z + 1) = 0
z + 1 = 0 or 4z^3 - 4z^2 + z + 1 = 0
z = - 1 or 4z^3 - 4z^2 + z + 1 = 0
z = - 1 or z = -0.3478448987
cos x = -1 or cos x = -0.3478448987
x = pi or x=1.9260678 or x = 4.357 [/b]
yes, but this is an add maths question.
how do u factorise to -0.3478448987 with a non-graphical
calculator?
tat is the tricky part. or else why we need to think so long?
got graphical calc i also can find. on paper how? use
newton-raphson?
