



 
Hi Jocelyn, By your notation and the fact that you are to use the Pythagorean Theorem only I think you have a right triangle with angles A, B and C where C is the right angle and sides of length a, b and c as in the diagram below. If this is correct the the Pythagorean Theorem tell us that
and hence if you know two of a, b and c you can find the third. For example if a = 9 and c = 15 then
Similarly if you know the definitions of the trig functions you can solve for the trig functions in your examples. For example if sinA = 12/15 then a = 12 and c = 15. From the calculation above using Pythagoras Theorem you know that b = 12 and thus
I hope this helps,  


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