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What is the value of cos(22.5) in roots????? WITH FULL PROCESS

Ayush Kumar , 7 Years ago
Grade 10
anser 1 Answers
Vaibhav Singh

Last Activity: 7 Years ago

\cos45 = cos(2x22.5)
=> cos(2x22.5)  = \cos2(22.5) – \sin2(22.5)
= 2\cos2(22.5) -1 
=> 2\cos2(22.5) –1 = 1/\sqrt{2}
=>2\cos2(22.5) = (\sqrt{2} + 1)/\sqrt{2}
=> \cos2(22.5) = (\sqrt{2} + 1)/2\sqrt{2}
=> \cos(22.5) = \sqrt{(\sqrt{2} + 1)/2\sqrt{2}}

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