Question

find cos 2theta when cos in 2nd quadrant .. sin =3/5
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Answer 1

Given,

cos x lies in 2nd quadrant

and sin x = 3 / 5

To Find,

cos 2x

Step by step explanation,

cos 2x = 1 - 2sin²x

cos 2x = 1 - 2. ( 3 / 5 )²

cos 2x = 1 - 2 * 9/25

cos 2x = 1 - 18/25

cos 2x = 7 / 25

Answer:

7 / 25

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