Author Topic: Finding the right angle in an equation (Read 1221 times) Tweet Share

/0 · « **on:** April 09, 2008, 09:36:45 pm »

$\mbox{For}\ \pi < x < \frac{3\pi}{2}\ \mbox{with}\ \sin{x}=-\sin{\frac{\pi}{6}},\ \mbox{find the value of x} \left(\mbox{do not evaulate}\sin{\frac{\pi}{6}}\right)$

Every time I keep getting $\frac{11\pi}{6}$ ... this isn't in the domain but I think it is an equivalent angle. I don't know how to make it so that it is within the domains though. My teacher used a pictorial method with the unit circle but I'm lazy and I would rather use identities.

AppleXY · « **Reply #1 on:** April 09, 2008, 09:43:22 pm »

-sin(pi/6) = sin(-pi/6)

sin is neg @ $\pi +\theta$

$\therefore \frac{\pi}{6}+\pi$

= $\frac{7\pi}{6}$

/0 · « **Reply #2 on:** April 09, 2008, 09:48:55 pm »

Thanks, ApppleXY, I was a bit confused about using the symmetry properties in reverse.

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Author Topic: Finding the right angle in an equation (Read 1221 times) Tweet Share

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Finding the right angle in an equation

AppleXY

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