Question

The value of cos(-330°) =
(a)-√3/2
(b)√3/2
(c) 1/2
(d) none of these.
​

Answer 1

Answer:

Remember that

cos

(

a

−

b

)

=

cos

(

a

)

cos

(

b

)

+

sin

(

a

)

sin

(

b

)

and that

330

º

=

360

º

−

30

º

, so

cos

(

330

º

)

=

cos

(

360

º

−

30

º

)

=

cos

(

360

º

)

cos

(

30

º

)

+

sin

(

360

º

)

sin

(

30

º

)

The cosine, sine, tangent and secant of 360º equal the cosine, sine, tangent and secant of 0º respectively. We know that

sin

0

º

is 0, and that

cos

0

º

=

1

so

cos

(

330

º

)

=

1

⋅

cos

(

30

º

)

+

0

⋅

sin

(

30

º

)

cos

(

330

º

)

=

√

3

2

Answer 2

Answer:

cos(330º)=√32. Explanation: Remember that cos(a−b)=cos(a)cos(b)+sin(a) sin(b) and that 330º=360º−30º , so.

Step-by-step explanation:

The sine, cosine and tangent of negative angles can be defined as well. ... The angle POQ is 30° and is called the related angle for 330°. ... a sin 120° b cos 150° c tan 300° d cos 240°.

ANS--( D )

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