This gives the meaning of the terms as generally understood in the middle of the 18th century. Robert Hooper's Physician's Vade-Mecum, published in 1812 has been used as a source of terms in the early 19th century; many of the terms mentioned are still in common use.
In either case, the value at x = 0 is defined to be the limiting value sinc(0) = 1. The normalization causes the definite integral of the function over the real numbers to equal 1 (whereas the same integral of the unnormalized sinc function has a value of Ï).
Solution to Question 1: 1  To find sin (x/2), we use the following half angle formula. 2  sin (x/2) = + or-SQRT [ (1 - cos x) / 2 3  ]. sin (x/2) = SQRT [ (1 - cos x) / 2 4  ]. Given that sin (x) = 1 / 4, we use the trigonometric identity sin x + cos x = 1 to find cos x, noting that x is in quadrant 2 and cos x is negative.uestions 2: x is in quadrant 3, approximate sin (2 x) if cos (x) = - 0.2. Round your answer to two decimal places. Solution to Question 2: 1  sin (2x) may be calculated using the double angle trigonometric identity. 2  sin (2x) = 2 sin (x) cos (x).