xcosΩ/a+ysinΩ/b=1,xsinΩ/a-ycosΩ/b=1 求证：x^2/a^2+y^2/b^2=1 坐等牛

xcosΩ/a+ysinΩ/b=1,
(xcosΩ/a+ysinΩ/b)^2=1,
即(xcosΩ/a)^2+2*xcosΩ/a*ysinΩ/b+(ysinΩ/b)^2=1,
xsinΩ/a-ycosΩ/b=1
(xcosΩ/a-ysinΩ/b)^2=1,
即(xcosΩ/a)^2-2*xcosΩ/a*ysinΩ/b+(ysinΩ/b)^2=1,
两式相加,得
x^2/a^2+y^2/b^2=2