Well I just failed a trig test.
Any help on why I did things wrong or what went wrong in my thought process? I triple checked all my answers and was positive I had 100 percent on this test, instead I got like 30 percent.
1) Show that $\tan^2 \theta - \sin^2 \theta = \tan^2 \theta \sin^2 \theta$
I turned the left side into $(\sin\sin)/\cos\sin$ which cancels out into $\sin^2/\cos^2 \sin^2$ whichs is $\tan^2 \sin^2$
2) I was suppose to "evaluate" (no idea what that means) cos 105 degrees and I got $-\sin 15$ degrees, which is wrong. I am supose to find the value of that but I have no idea how without a calculator.
4) evaluate $\tan a/2$ if $\sin^2a = .64$ and $a$ is in quadrant II I got $\tan = 1$ but in my work I forgot I negative sign and got the whole problem wrong.
5) show that $\sin3a = \sin3a - 3\sin - 4 \sin ^3 a$
I know that $3\sin a = \sin^3a$ so I reduced that to $a$ and I know $A = A - 4\sin^3$ is impossible, no number can equal itself minus 4 times something besdies 0 and $\sin$ can't equal zero for that value.
6) evaluate ($\tan83$ degrees - $\tan 38$ degrees)/ ($1+\tan 83$ degrees $\tan38$ degrees) I know that is equal to $\tan(A-B)$ and from that I got $8/8 - 1/8$ somehow equaling $7/8$ not sure where I went wrong here.
8) express $\cot 2a$ in terms of $\cot a$
I made this simple $\cot a + \cot a2a / 2$
Not sure why that is wrong, but I got all the points off.
9) simplify $(1+\tan^2\theta)/(1+\cot^2\theta)$ I made that $\sec^2/\csc^2$ which turns into $\sec^4$ I got this wrong somehow.
I always mess up tests like this for some reason, not sure what to do to pass classes. I still mess up simple math, was looking at someone's homework for math 70 and I couldn't do most of it. I probably need to drop out of this class since I am failing highschool math in college, and go back to math 70 or whatever.