The triangle ABC has sides AB  AC  and BC , as well as cosBaC 
a] Write down and simplify a quadratic equation satisfied by and hence evaluate
b] Express sinBaC in the form
c] Express sinAcB in the form
I have no idea how to solve these, it's the most difficult question I have out of the exam papers and even though I (sort of) understand trigonometry at the moment this is just impossible to me.
Could anyone please help?
For a] I have a value of 8, and this I know to be right
For b] I have but I don't know how you can express it in the form asked for.
Please could someone help?