Triangles Test Corrections

The only problem I lost points on was the derivation of the law of cosines. I got the equations x^2+h^2=c^2 and (a-x)^2+h^2=b^2, but I couldn't connect them.
Here is how to connect the two equations:
First, factor out the (a-x)^2 to make the equation a^2-2ax+x^2+h^2=b^2
Then, replace the x^2+h^2 with c^2 using substitution to make the equation a^2-2ax+c^2=b^2.
Using the picture, it is possible to determine that cosB=x/c, or x=c(cosB).
Therefore, we can substitute this for x, making the final equation a^2+c^2-2ac(cosB)=b^2, or the law of cosines.

I am good at geometry so I liked this unit. I only had to memorize the formulas and apply them, which is what I am good at in math.

Trigonometry and Unit Circle Test Corrections

1) In this problem, I made the mistake of saying that the radius of the circle was 100 rather than 10. I forgot that the equation of a circle is x^2+y^2=r^2. Knowing this, the radius would be the square root of 100, or 10.

7) In this problem, I lost all of my points for not paying attention to negatives. The point was in the second quadrant, therefore everything except for the sine should be negative. I made them all positive.

9) e. I did not simplify -2(squareroot2)/2 to -(squareroot2) by cancelling the 2's.
g. 5pi/6 is in the second quadrant, therefore the sine should be positive, but I wrote -1/2.

After memorizing the unit circle, this unit was not too bad. It is easy to make silly mistakes, however.