Question

What is the sine value of 7 pi over 6?

Answer 1

Since
`\sin(\pi-x)=\sin x`, you have


`\sin\frac{7\pi}6=\sin\left(\pi-\frac{7\pi}6\right)=\sin\left(-\frac\pi6\right)`

and since
`\sin x` is odd, i.e.
`\sin(-x)=-\sin x`, you have


`\sin\frac{7\pi}6=-\sin\frac\pi6=-\frac12`