Consider the following points on the graphs of \(y = cos(x)\) and,\(y = \cos(x + \pi/6) \) with the added vertical dashed lines:
Then what are 10c and 10d in that order?
+118609 I will do the more difficult one and then you can almost copy and do the easier one.
'a' is a negative number so to stop my own confusion I let a=-t (so t is positive)
Now
cos(-t) = 0.8 (4th quad)
cos(t)=0.8
\(c=cos(-t+\frac{\pi}{6}) \\ c=cos(\frac{\pi}{6}-t )\\ c=cos(\frac{\pi}{6})cos(t)+sin(\frac{\pi}{6})sin(t)\\ c=\frac{\sqrt3}{2}*0.8+\frac{1}{2}*0.6\\ 10c=\frac{\sqrt3}{2}*8+\frac{1}{2}*6\\ 10c=4\sqrt3+3\)
If you do not understand then ask specific question, the mothod is almost identical.
LaTex:
c=cos(-t+\frac{\pi}{6}) \\
c=cos(\frac{\pi}{6}-t )\\
c=cos(\frac{\pi}{6})cos(t)+sin(\frac{\pi}{6})sin(t)\\
c=\frac{\sqrt3}{2}*0.8+\frac{1}{2}*0.6\\
10c=\frac{\sqrt3}{2}*8+\frac{1}{2}*6\\
10c=4\sqrt3+3
