15. Convert x(t) = 5 cos(10t+30) + 2 sin(10t - 20) + 6 cos(10t+80) into a single sinusoid as in Problem 13. 16. Find the delay between x1(t) = cos(10t+20) and x2(t)=sin(10t - 10). 17. Equations 2.23 and 2.24 were developed to convert a sinusoid such as cos(wt - 0) into a sine and cosine wave. Derive the equations to convert a sinusoid based on the sine function, sin(wt + 0), into a sine and cosine wave. (Hint: Use the appropriate identity