Is this a sinusoid?
No. because 2 pie x and 5 pie x are not the same/equal.?
A sine wave or sinusoid is a mathematical curve that describes a smooth repetitive oscillation. When you add/subtract two sinusoids of differing frequencies, you get a combination wave of two frequencies, the sum, and the difference. In this problem, you see the sum(7PI) and the difference(2PI) added for form a repetitive non-smooth curve.
posted by bobpursley
Okay so it is not since it is a non-smooth curve not a smooth curve.posted by Anonymous
huh? surely it is smooth, as are all sums of sines and cosines.
and it's PI. not PIE! Pie is what you eat.
sin2πx-cos5πx has a period of 2
It is not a simple sine wave, but it is sinusoidal, as shown here:
http://www.wolframalpha.com/input/?i=sin2%CF%80x-cos5%CF%80xposted by Steve