Cos 120 Degrees

Did you get a 120 degree cos with a double angle formula? 3

cos 2A = cos 2A sin 2A

cos 2 (60 °) = cos 2 (60 °) sin 2 (60 °)

cos 2 (60 °) = (cos60 °) 2 (sen60 °) 2

cos 2 (60 °) = (1/2) 2 (š š3) / 2) 2

cos 2 (60 °) = 1/4 3/4

cos 2 (60 °) = 2/4 or 1/2 (answer)

Help for example!

Because 120

The formula for cos (± +) is cos ± cos Ÿ sin ± sin. But if Ÿ = Â, then the formula is:

cos (± ± + ±) = cos 2 ± ± = cos ± cos ± sin ± sin ± ± = cos² ± sin².

Let's say ± = 60. So 2ÃŽÂ ± = 120Â °, and according to the double angle formula, see, this is correct:

cos 120 ° = cos² 60 ° sin² 60.

cos 60 ° =

Sen 60 ° = (à ˆš3) / 2.

By adding a 60% cosine and sign to the formula, we get the following:

cos 120 ° = (ý) ² [(à š3) / 2]

cos 120 ° = ¼ 3/4

cos 120 ° = (1 3) / 4

cos 120 ° = 2/4

120 ° = cos.

Check with your pocket calculator that 120 ° =.

Sin 120 = 2 Sin 60 cos 60

Sin 120 = 2 * (1/2) Square 3 * (1/2)

Sin 120 = (1/2) square 3

cos 120 = square [1 sin 2120]

cos 120 = square [1 (3/4)]

cos 120 = square (1/4)

cos 120 = 1/2

cos120deg = cos (60 + 60) = cos60cos60sin60sin60 (1/2 * 1/2) (3) 1/2/2] 2 1/43/4 2/4

cos120 = cos (90 + 30)

The shape of which is cos (A + B) = cosAcosB sinAsinB.

=> cos120 = cos (90 + 30) = sin90.sin30

= 0 1/2

cos120 = 1/2.

But I helped!

Cos 120 Degrees