Analysis of the voltage in a hairdryer involves terms of the form\( \sin(nwt-90^{\circ})\), where n is a positive integer, w is the frequency of the voltage, and t is time. Use an identity to simplify this expression.

Find the function The following limits represent the slope of a curve \(y=f(x)\) at the point \(\{a,f(a)\}\) Determine a possible function f and number a, then calculate the limit \(\lim_{x\rightarrow2}\frac{5\cdot x^2-20}{x-2}\)