Explaining The Universe on Instagram: "Sine and cosine waves are identical in shape, amplitude, and frequency, differing only by a phase shift. A sine wave starts at zero and rises, while a cosine wave starts at its maximum value. Mathematically, a cosine wave is just a sine wave shifted left by 90 degrees (π/2 radians). Because of this, the choice between sine and cosine usually depends on where the motion or signal begins in time. In physics and engineering, sine waves are often used when a sy