Posted by Joel on October 22, 2002 at 22:22:29:
In Reply to: here's the solution, THANKS LOTS for the help! posted by Helen on October 22, 2002 at 20:47:06:
: Sin(y)Cos(x+y) >= 0
: Sin(y) and Cos(x+y) have the same sign.
: 'Cos' is 2Pi periodic and is positive half the time and negative half the time
: (ignoring zeros, which have no effect). So, for each value of y, exactly half
: of the x-values between 0 and 2Pi give Cos(x+y) to have the same sign as
: Hence, exactly half of the (x,y) values in the region 0<=x<=2Pi, 0<=y<=2Pi
: (whose area is 4xPi^2) satisfy the condition, giving the area of the region R
: as 2xPi^2.
Sin(y)Cos(x+y) >= 0 :
what kind of "region" is this? on what kind of coordinate system?
Sin(y) as a function of ... what?
Cos(x+y) as a function of ... what?
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