The Student Room Group
Reply 1
BLUREMI
its q 29 on page 128

u have to use parametric equations

an eclipse is given by

x= 3cost, y= 2sint

a) find the area of the finite region bounded by the eclipse and the positive x and y axis

after intergration i have -3t + 3sin2t/2 is that right and how do u get the limits


Your answer's right and the integral's limits are from pi/2 DOWN TO 0
Reply 2
RichE
Your answer's right and the integral's limits are from pi/2 DOWN TO 0


oh yeh thanks, but the answer i get is -3pie/2 the answer is 3pie/2 is does it matter
Reply 3
BLUREMI
oh yeh thanks, but the answer i get is -3pie/2 the answer is 3pie/2 is does it matter


Yes that's why I said the limits are from pi/2 DOWN TO 0. We normally have the dummy variable increasing in size.

So what I mean by that the limit at the TOP of the integral is 0 and the limit at the BOTTOM is pi/2.

This will give you a positive answer - as it ought because it's representing an area.