Radian Measure: find theta, given sin(theta)=-sqrt(3)/2 and

[hynson]

Hey guys. This one question simply has me stumped. I'm not sure how to write all those fancy symbols such as theta on here so I'll give you a key chart. lol

σ = theta ` = degrees

Find σ, if 0${\displaystyle <\sigma <360}$ and...

sinσ = -sqrt(3)/2 and σ in QIII (Quadrant 3)

Thank you!

The answer is 240`, but I keep getting 300'.

 

[pka]

Well the reference angle is $\displaystyle 60^o$.

 

[galactus]

Remember, quad III: $\displaystyle {\pi}\ to\ \frac{3{\pi}}{2}$

$\displaystyle {\theta}=\frac{4{\pi}}{3}\ and\ \frac{-\pi}{3}$

You're using quad IV.

Think of the reference angle being $\displaystyle \frac{\pi}{3}=60$