The expression "iθ" involves the imaginary unit "i," which is defined as the square root of -1, and "θ," a variable often representing an angle in radians. This notation is commonly used in mathematics, particularly in complex numbers and trigonometry. When combined, "iθ" can represent points on the complex plane, where the real part is zero and the imaginary part is determined by the angle θ. In the context of Euler's formula, which states that e^(iθ) = cos(θ) + i sin(θ), "iθ" plays a crucial role in connecting exponential functions with trigonometric functions. This relationship is fundamental in various fields, including engineering, physics, and signal processing, as it simplifies the analysis of oscillatory behavior and waveforms.