If sin A = and A is in the 3rd quadrant, find exact values of:

(i) cos A (ii) tan A (iii) sin 2A

I guess im sort of confused what is being asked, the way I attempted it was:

Assuming Sin A =

Then A = Arcsin( )

Then A = -.476

SO

(i) cos(-.476) = .889

(ii) tan(-.476) = -.515

(iii) sin(-.952) = -.814

Am I anywhere near close on this one ?, Thanks in advance for any help.