Question

Math 3: First question on the attached file

Answer 1

Answer:

cos ( 330 º ) = √ 3 /2

Explanation:

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

Hope This Helps! Have A Nice Day!!

Answer 2

Explanation:

cos 330°=cos ( 360 -30)

In fourth quad the value of cos A is positive .

All angles when subtracted by multiple of 180° or (π) the function remain same

cos (30°)=√3/2

Also-

Cos(330)=Cos(360–30)

since Cos(360-x)=cos(x) where x is in degree

Cos(330)=Cos(30)= √ 3 /2 ~ 0.866