cos-pi-8-with-solution-plz-

Question Number 156058 by VIDDD last updated on 07/Oct/21

c o s \frac{π}{8} = \dots ? w i t h s o l u t i o n p l z

Answered by cortano last updated on 07/Oct/21

\cos \frac{π}{4} = 2 \cos^{2} \frac{π}{8} - 1

\cos \frac{π}{8} = \sqrt{\frac{1 + \cos \frac{π}{4}}{2}}

Commented by puissant last updated on 08/Oct/21

\Rightarrow c o s \frac{π}{8} = \sqrt{\frac{1 + \frac{\sqrt{2}}{2}}{2}} \Rightarrow c o s \frac{π}{8} = \frac{\sqrt{2 + \sqrt{2}}}{2} . .