Hello ! I cant remember how to solve this... please help me
Find all the solutions in the intervall [-4pi; 4pi] for
a) sin(x) = 0.23
b) cos(x) = -0.9
c) tan(x) < 1
(a) solutions are in quads I and II
going from $\displaystyle 0$ to $\displaystyle 4\pi$ ...
$\displaystyle x = \arcsin(.23)$ , $\displaystyle \pi - \arcsin(.23)$ , $\displaystyle 2\pi + \arcsin(.23)$ , $\displaystyle 3\pi - \arcsin(.23)$
.. now you go from $\displaystyle 0$ to $\displaystyle -4\pi$
(b) solutions are in quads II and III
from $\displaystyle 0$ to $\displaystyle 4\pi$ ...
$\displaystyle x = \arccos(-0.9)$ , $\displaystyle 2\pi - \arccos(-0.9)$ , $\displaystyle 2\pi + \arccos(-0.9)$ , $\displaystyle 4\pi - \arccos(-0.9)$
get the idea?
for (c) , look at the graph.