Given that arccos (x) = b.
what are all the angle measures for right triangle abc?
a = 20°, b = 70°, 90°
a = 60°, b = 30°, 90°
a = 450, b = 45°, 90°
a = 55°, b = 35°, 90°

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.