Question

If cosx =1/5
then value of
of cos (2x) is
​

Answer 1

Answer:

-23/25

Step-by-step explanation:

cosx = 1/5

cos2x = ?

cos2x = Cos²x - Sin²x

= 2Cos²x - 1 (1= Sin²x + Cos²x)

= 2(1/5)(1/5) - 1

= 2(1/25) - 1

= 2/25 -25/25

= -23/25