Trigonometrical functions Signs

Table 2.4 The signs of the trigonometric functions sin, cos and tan in each of the four...

Now, however, in the range of values chosen for 6, cos0 is always positive. Thus we may remove the absolute value signs from cos 6 in the denominator. (This is one of the reasons that the principal values of the inverse trigonometric functions are defined as they are.) Then the cos0 terms cancel, and the integral becomes... 

The magnitude and sign of trigonometric functions are presented in Table 1.3. 

When an equation is too long to fit on one line, break it after an operator that is not within an enclosing mark (parentheses, brackets, or braces) or break it between sets of enclosing marks. Do not break equations after integral, product, and summation signs after trigonometric and other functions set in roman type or before derivatives. 

The derivatives of the hyperbolic functions are easily found from their exponential forms (4.57). These are analogous to the trigonometric results, except that there is no minus sign ... 

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