Question

if cos A = √√2+1/2√2 then find the value of cos 2a​

Answer 1

Answer:

Ok...

Step-by-step explanation:

$\cos(a) = \frac{ \sqrt{ \sqrt{2} + 1} }{2 \sqrt{2} }$

...

And Cos (2a) = 2 cos² (a) - 1,

Implies that...

$\cos(a) = 2 \times \frac{ \sqrt{2} + 1 }{8} - 1$

$= \frac{ \sqrt{2} + 1 }{4} - 1$

$= \frac{ \sqrt{2} - 3}{4}$

( Required answer)

Answer 2

Step-by-step explanation:

given that:

cosA =√(√2+1/2√2)

so cos2A=1/√2