Hi

I need help on the following two questions:

1) An angle is measured at 2.1 radians.

a) What is its measure in degrees, minutes and seconds ( to the nearest second)?

b) What is its sine?

This is what i have done:

To convert radians to degrees you multiply by $\displaystyle \frac{180}{\pi}$

so get 120 degrees.

to get minutes i multiplied by 60 and to get seconds i multiplied by 3600

therefore it is: 7200mins, 432000seconds

How would i find the sine??

2) Write down 4 values of x (exactly, in radians) for which $\displaystyle sinx = \frac{-1}{2}$ and circle the value which equals $\displaystyle arcsin(\frac{-1}{2})$?

This is what i have done:

So firstly i wrote down when sin is -0.5, which is in the 3rd and 4th quadrant.

i know that $\displaystyle sinx = -0.5 = \frac{\pi}{6}$

so...

$\displaystyle \pi + \frac{\pi}{6}, 2\pi - \frac{\pi}{6}, 2\pi + \frac{\pi}{6},

3\pi - \frac{\pi}{6}$

final values are: $\displaystyle \frac{7\pi}{6}, \frac{11\pi}{6}, \frac{13\pi}{6},

\frac{17\pi}{6}$

Not sure if this is correct.

P.S