Question

can u tell me cos120 value

Answer 1

HEY FRIEND HERE IS UR ANS:

⌛The exact value of cos(120°) is -1/2.

We can find this exact value by using the double angle identity for cosine.

✴Double Angle Identity: cos(2x) = cos2 (x) - sin2 (x)

✴We will also need the following facts:

120 = 2 × 60
sin(60°) = √(3) / 2
cos(60°) = 1/2

✴Since 120 = 2 × 60,
we have the following:

cos(120°) = cos(2 × 60°)

✴Therefore, we can use our double angle identity for cosine with x = 60.

cos(120°) = cos(2 × 60°)
= cos2 (60) - sin2 (60)

✴Now we use facts two and three to plug in values for cos(60°) and sin(60°), and then we simplify.

cos(120°) = cos(2 × 60°)
= cos2 (60) - sin2 (60)
= (1/2)2 - (√(3) / 2)2 
= 1/4 - 3/4
= -2/4
= -1/2

✴We end up with cos(120°) = -1/2.

I hope it was helpful.
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Answer 2

Answer:

HELLO DEAR☺️

cos120

=cos(90+30)

=-sin(30)

= -½