How do you eliminate the parameter theta to find a cartesian equation of the curve: x=sin(1/2 theta), y=cos(1/2 theta), 0 is less than or equal to theta and theta is less than or equal to 4pi

The answer to the problem is as follows:

x = sin(t/2) 
y = cos(t/2) 

Square both equations and add to eliminate the parameter t: 

x^2 + y^2 = sin^2(t/2) + cos^2(t/2) = 1 

The final step is translating the original parameter limits into limits on x and y. Over the -Pi to +Pi range of t, x varies from -1 to +1, whereas y varies from 0 to 1. Thus we have the semicircle in quadrants I and II: y >= 0.

40%=2/550=1/230=3/1056=14/25

X= 2 he can buy 2 packs of cards for $12 and an action figure for $3 so he would spend $15 in total plus the free poster