To find A, we need to take the derivative of the given function:
ddx[−−17.6sin(34.4−5.2x)] = −5.2*17.6cos(34.4−5.2x)
= −91.52cos(34.4−5.2x)
Comparing with the given function:
AcosB = −91.52cos(34.4−5.2x)
Therefore, A = |-91.52| = 91.52
Hence, A is 91.52.