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(i) Draw sketches of the functions sin x and [itex]sin^2x[/itex] over the range -360<x<360.

(ii) Explain why, for the range 0 < x < 90=2, sin x is smaller than tan x.

(iii) Using the equality [itex]cos^2x=\frac{1}{2}(1+cos2x)[/itex] or otherwise, express

[itex]cos^4x[/itex]in terms of cos2x and cos4x.

My attempt at part iii:

I squared the left hand side of [itex]cos^2x=\frac{1}{2}(1+cos2x)[/itex] to get [itex]cos^4x[/itex] and therefore squared the right hand side as well, leaving the right hand side as [itex]\frac{1}{4}(1+cos2x)^2[/itex]

I'm presuming I have to square the right hand bracket out but I'm unsure on what (cos2x)^2 becomes.

Any help would be appreciated