We found the answer of 4.5. I had her add another 1.5 which gave us the number 6 in the chart to show proof to her.
Step-by-step explanation:
We have:
Then we use trigonometric identities to change the negative sign of the trigonometric functions, so:
We clear f(x):
we simply what we can:
Thus, the correct answer is;
-k=7
divide each side by -1
-k/-1 = 7/-1
k = -7