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If $1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \frac{1}{9} - \frac{1}{11} + \dots = \frac{π}{4},$ then value of $\frac{1}{1 \cdot 3} + \frac{1}{5 \cdot 7} + \frac{1}{9 \cdot 11} + \dots$ is

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Correct option is A

We have π4=1−13+15−17+19−111+⋯ =21⋅3+25⋅7+29⋅11+⋯⇒ 11⋅3+15⋅7+19⋅11+⋯=π8

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If 1−13+15−17+19−111+⋯=π4, then value of 11⋅3+15⋅7+19⋅11+⋯is

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If $1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \frac{1}{9} - \frac{1}{11} + \dots = \frac{π}{4},$ then value of $\frac{1}{1 \cdot 3} + \frac{1}{5 \cdot 7} + \frac{1}{9 \cdot 11} + \dots$ is