Chapter 5: Problem 5
The next two exercises emphasize that \(\cos \frac{\theta}{2}\) does not equal \(\frac{\cos \theta}{2}\). For \(\theta=6\) radians, evaluate each of the following: (a) \(\cos \frac{\theta}{2}\) (b) \(\frac{\cos \theta}{2}\)
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Chapter 5: Problem 5
The next two exercises emphasize that \(\cos \frac{\theta}{2}\) does not equal \(\frac{\cos \theta}{2}\). For \(\theta=6\) radians, evaluate each of the following: (a) \(\cos \frac{\theta}{2}\) (b) \(\frac{\cos \theta}{2}\)
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Find the angle between a side of length 5 and the side with length 9 in an isosceles triangle that has one side of length 9 and two sides of length \(5 .\)
Evaluate the indicated expressions assuming that $$ \begin{array}{ll} \cos x=\frac{1}{3} & \text { and } \sin y=\frac{1}{4} \\ \sin u=\frac{2}{3} & \text { and } \cos v=\frac{1}{5} \end{array} $$ Assume also that \(x\) and \(u\) are in the interval \(\left(0, \frac{\pi}{2}\right),\) that \(y\) is in the interval \(\left(\frac{\pi}{2}, \pi\right),\) and that \(v\) is in the interval \(\left(-\frac{\pi}{2}, 0\right) .\) $$\tan (u+v)$$
Show that $$\tan ^{2}(2 x)=\frac{4\left(\cos ^{2} x-\cos ^{4} x\right)}{\left(2 \cos ^{2} x-1\right)^{2}}$$ for all numbers \(x\) except odd multiples of \(\frac{\pi}{4}\).
Find a formula for \(\tan \left(\theta+\frac{\pi}{2}\right)\).
Show that $$\sin ^{2}(2 \theta)=4\left(\sin ^{2} \theta-\sin ^{4} \theta\right)$$ for all \(\theta\).
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