JEE MAIN - Mathematics Hindi (2020 - 9th January Evening Slot - No. 11)

यदि $$x = \sum\limits_{n = 0}^\infty {{{\left( { - 1} \right)}^n}{{\tan }^{2n}}\theta } $$ और $$y = \sum\limits_{n = 0}^\infty {{{\cos }^{2n}}\theta } $$

के लिए 0 < $$\theta $$ < $${\pi \over 4}$$, तो :
x(1 + y) = 1
y(1 – x) = 1
y(1 + x) = 1
x(1 – y) = 1

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