+1124 Hi friends,
I got stuck with this, and Google is not much help...please if someone would help me?
Determine without a calculator:
\({Cos72 \over{Sin24}}+{Sin72 \over{Cos24}}\)
This gives
\({Cos72Cos24+Sin72Sin24} \over{Sin24Cos24}\)
I do not see how to go further?..any help please?..Thank you kindly..
+1124 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..
+1124 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?
+118673 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.
