Albert
Posts:
282
Registered:
12/9/07


Re: Proving trigonometric identities
Posted:
Jan 24, 2009 5:02 AM


On Jan 24, 8:37 pm, Angus Rodgers <twir...@bigfoot.com> wrote: > Don't you mean a lower quadrant III or IV (assuming they are numbered > anticlockwise, starting from the positive quadrant, at the top right)? Yes; I made a mistake!
> >So then there are solutions to the > >equation, aren't there? and why/why not? > > I'm a bit blearyeyed, but it certainly does look to me as if (b) is > equivalent to sin x = 3/4, which has one solution for 180 degrees < > x < 270 degrees, one solution for 270 degrees < x < 360 degrees, and > no other solutions in the range indicated. (You'll need a calculator > to find the approximate values of x.)
I agree: assuming sin x = 3 /4 is a step that one should get to (or take the inverse cosec early on), x = 229, 311 degrees to the nearest degree.

