Question

Cos 2x, если sin x = -2/7

Answer 1

Ответ:

решение смотри на фотографии

Answer 2

Ответ:

41/49

Объяснение:

сos2x=cos²x-sin²x=1-2sin²x

сos2x=1-2(-2/7)²=1-8/49=49/49-8/49=41/49

Answer 3

To find the value of cos 2x when sin x = -2/7, we can use the trigonometric identity for cos 2x in terms of sin x.

The identity is: cos 2x = 1 - 2(sin x)^2

Given sin x = -2/7, we can substitute this value into the identity:

cos 2x = 1 - 2(-2/7)^2 = 1 - 2(4/49) = 1 - 8/49 = (49 - 8)/49 = 41/49

Therefore, cos 2x = 41/49 when sin x = -2/7.