Question

How is sin(pi/2 + x) equal to cos x ??

Answer 1

Magic, of course :)

Answer 2

Type it in to your calc

Answer 3

Yes. lol.

Answer 4

Or, the fact that
\[\Large \sin(\alpha+\beta) = \sin(\alpha)\cos(\beta)+\cos(\alpha)\sin(\beta)\]

Pick whichever reason you like :D

Answer 5

Or http://www.youtube.com/watch?v=n5RpLuWnCTs.

Answer 6

there is no button of x in the calculator @Ninagf99

Answer 7

in t 84 silver edition plus there is

Answer 8

Identities, @koli123able you should study them well :)
Plug in
\[\alpha = \frac\pi 2\]
and
\[\beta = x\]

And work out the magic :D