AM-2550

Double angle formulae

A Math · Secondary 4 · Hard · Double angle formulae

Without using a calculator, express

\sin 67.5^\circ

in the form

\sqrt{\dfrac{b-a}{b}}

, where

a

and

b

are integers.

$\sqrt{\dfrac{4+2\sqrt2}{8}}$
$\sqrt{\dfrac{4-2\sqrt2}{8}}$
$\sqrt{\dfrac{2+\sqrt2}{2}}$
$\sqrt{\dfrac{4-\sqrt2}{8}}$

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