Find the area of the shaded figureExpress result to the accuracy of 3 decimal.
Correct answers: 68
The first user who solved this task is Djordje Timotijevic.
Edison's phonographIn 1877, Thomas Edison announced his invention of his “talking machine” - the tin-foil cylinder recorder that preceeded the phonograph. He appears to have envisioned it as a business dictation machine. In Sep 1877, he wrote that its purpose was “to record automatically the speech of a very rapid speaker upon paper; from which he reproduces the same Speech immediately or years afterwards preserving the characteristics of the speakers voice so that persons familiar with it would at once recognize it.” The indented tin foil, however, would survive only a few playings. By the first public showing of a phonograph, which took place in New York City in early Feb 1878, its practical applications had not yet been realized.[Image: from Scientific American, 22 Dec 1877]