Amplitude of a sin + cos expression used in SHM

In class there was a query about the form of the equation: A = BcosDx + CsinDx. This simple example allows you to change parameters A B C D and gives the value of the magnitude (Amplitude) of the resultant: A = sqrt(B^2 + D^2).
Biuld up f(x) the g(x). Change the amplitude and frequency of each. View h(x) - the sum of the cos and sin expressions. Note the total amplitude A for given examples of B and C. Confirm the formula used: A = sqrt(B^2 + D^2)