Question 609501
1. a)   tan^-1(-1/4)      b)    cos^-1(-1/4)
The range for tan^-1 is {{{-pi/2}}} through {{{pi/2}}}. And since the argument is negative, tan^-1(-1/4) will have a value between 0 and {{{-pi/2}}} (i.e. negative). The range for cos^-1 is 0 to {{{pi}}}. And since the argument is negative, cos^-1(-1/4) will have a value between {{{pi/2}}} and {{{pi}}}. Positive is larger than negative.<br>
2. a)   sin(4pi/5)        b)    cos(4pi/5)
{{{4pi/5}}} is in the second quadrant. sin is positive in the second quadrant and cos is negative in the second quadrant. Again, positive is larger than negative.