Question

sin 150

Answer 1

Noted.

Answer 2

\(\large\color{black}{ \sin(150)=\sin(180-30) }\)

there is a rule: \(\large\color{black}{ \sin(a-b)=\sin(a)\cos(b)-\cos(a)\sin(b) }\)

So apply it here: \(\large\color{black}{ \sin(180-30)=\sin(180)\cos(30)-\cos(30)\sin(180) }\)

we are given that:
\(\large\color{black}{ \sin(180)=0 \\\cos(180)=0 }\)

Answer 3

I think you mean:
\(\cos(90)=0, \cos(180)=-1\)

Answer 4

Yes, my bad cos(180)=-1,

if you draw a 30-60-90 triangle

(knowing that
~ cosine = adjacent/hypotenuse
~ sine = opposite/hypotenuse )


and from the picture find cos(30 and sin(30)