# If sin36=a, express each of the following in terms of a

• September 3rd 2012, 08:46 AM
VegetaZA
If sin36=a, express each of the following in terms of a
This is the first time that I am doing these sections in trig so I need detailed answers. If possible, please do the answers first and then give the explanations. Please try and answer as many questions possible.
http://s10.postimage.org/vzu7cpftl/scan0001.jpg

I need these answers ASAP so that I can study for a test.

• September 3rd 2012, 08:47 AM
Prove It
Re: If sin36=a, express each of the following in terms of a
You're not going to get full solutions here. Show what you have tried, then we can give you some more guidance.
• September 3rd 2012, 08:49 AM
VegetaZA
Re: If sin36=a, express each of the following in terms of a
I would love to try it but I've never done this before. I've only done basic trig and that is why I'm asking for detailed answers.
• September 3rd 2012, 11:48 AM
HallsofIvy
Re: If sin36=a, express each of the following in terms of a
All of these can be done using basic trig. And that is how you do mathematics- you try something and if it doesn't work, try something else. In problem 1, do you notice that every one of those angles can be written as 36 plus or minus some multiple of 90? Surely in "basic trig" you learned that $sin^2(x)+ cos^2(x)= 1$. One of these uses that directly!
• September 3rd 2012, 09:09 PM
VegetaZA
Re: If sin36=a, express each of the following in terms of a
I've worked out some of them. Will post pics of it later today:)