Question

X by a cos theta + y by b sin theta is equal to 1 and second bracket is x by a sin theta minus y by b cos theta is equals to 1 and we have to prove that x square by a square plus y square by b square is equals to 1

Answer 1

I will give a clue.some times this may help u
since both are equal to 1
x/a cos theta+y/b sin theta=x/a sin theta-y/b cos theta