12-1-2-9π-8π-7π-6π-5π-4π-3π-2ππ



Find a sinusoidal function that matches the given graph. If needed, you can enter π\displaystyle \pi=3.1416... as 'pi' in your answer, otherwise use at least 3 decimal digits.

f(x)=\displaystyle {f{{\left({x}\right)}}}=