A=30 degrees, a=9 and b=8. Find the missing sides/angles. I did cos39=x/8 and reduced that to 8cos39=x. I got 6.92. But that's not a valid answer, so I can't go from there. What did I do wrong? Can you show me how to get the other answers as well, please?

Question

A=30 degrees, a=9 and b=8. Find the missing sides/angles. I did cos39=x/8 and reduced that to 8cos39=x.  I got 6.92.  But that's not a valid answer, so I can't go from there.  What did I do wrong? Can you show me how to get the other answers as well, please?

bobpursley · Answer

Law of sines: a/SinA = b/SinB solve for B from that. Then solve for C knowing A and B, and the sum of angles is 180 Then, find c with the law of sines, or law of cosines.

Dan · Answer

If the sine of an angle is 3/5 and the angle is not in quadrant 1, what are the remaining five trigonometric values for that angle?