Question

Use the following information to determine cos(2x).

cos(x)=3/5 and sin(x) is negative

Answer 1

Hey !!!

sinx = 3/5 ( given )

We know a formula of cos2x = ( 1 - 2sin²x)

putting the value of sinx on value of cos2x = ( 1 - 2sin²x)

hence,

we get

cos2x = ( 1 - 2sin²x )

=> [1 - 2 × ( 3/5 )² ]

=> [ 1 - 2 × 9 /25 )

=> [ 25 - 18 /25 ]

=> 7/25 Answer ✔