Cos 72

Tiggsy,

Yes, I see,

The top would then be

$Cos(72-24)$

but the bottom part...I really do not see how to re-write that..

I have here something that shows that (Sin(x)Cos(x)) can be written as ${1 \over2}(2SinxCosx)$

How do they get to that?..please?

You need to memorize

$sin(A+B) = sinAcosB + cosAsinB\\ so\\ sin(2A)=sinAcosA+cosAsinA=2sinAcosA$

It can be provben of course but you really need to memorize it.

so Sin24cos24 can be written as   0.5(2sin24cos24) = 0.5*sin48

Note: I have not looked at the whole question.