Double-Angle Trig Identities

Write as a single trig function of a single angle.
 $2\sin\frac{\pi}{5}\cos\frac{\pi}{5}$  

•  $\sin\frac{\pi}{10}$  

•  $\sin\frac{2\pi}{5}$  

•  $\cos\frac{2\pi}{5}$  

•  $\cos\frac{\pi}{10}$  

Tags

CCSS.HSF.TF.C.9

Write as a single trig function of a single angle:
 $\cos^232\degree-\sin^232\degree$  

•  $\cos64\degree$  

•  $\cos16\degree$  

•  $\sin64\degree$  

•  $\sin16\degree$  

Tags

CCSS.HSF.TF.C.9

Write as a single trig function of a single angle:
 $\frac{2\tan140\degree}{1-\tan^2140\degree}$  

•  $\tan140\degree$  

•  $\tan70\degree$  

•  $\tan280\degree$  

•  $\cot280\degree$  

Tags

CCSS.HSF.TF.C.9

 $\sin x=\frac{12}{13}\ \ and\ \ \frac{\pi}{2}<x<\pi$  

Find the exact value of  $\sin2x$ .

•  $-\frac{120}{169}$  

•  $\frac{120}{169}$  

•  $-\frac{119}{169}$  

•  $\frac{120}{119}$  

Tags

CCSS.HSF.TF.C.9

 $\sin x=\frac{12}{13}\ \ and\ \ \frac{\pi}{2}<x<\pi$  

Find the exact value of  $\cos2x$ .

•  $-\frac{120}{169}$  

•  $\frac{119}{169}$  

•  $-\frac{119}{169}$  

•  $\frac{120}{119}$  

Tags

CCSS.HSF.TF.C.9

 $\sin x=\frac{12}{13}\ \ and\ \ \frac{\pi}{2}<x<\pi$  

Find the exact value of  $\tan2x$ .

•  $-\frac{120}{119}$  

•  $\frac{119}{169}$  

•  $-\frac{119}{169}$  

•  $\frac{120}{119}$  

Tags

CCSS.HSF.TF.C.9

 $\cos\theta=\frac{4}{5}\ \ and\ \ \frac{3\pi}{2}<\theta<2\pi$  

Find the exact value of  $\sin2\theta$ .

•  $-\frac{1}{5}$   

•  $\frac{24}{25}$  

•  $-\frac{24}{25}$  

•  $-\frac{25}{24}$  

Tags

CCSS.HSF.TF.C.9

 $\cos\theta=\frac{4}{5}\ \ and\ \ \frac{3\pi}{2}<\theta<2\pi$  

Find the exact value of  $\cos2\theta$ .

•  $-\frac{1}{5}$  

•  $\frac{7}{25}$  

•  $-\frac{7}{25}$  

•  $-\frac{25}{7}$  

Tags

CCSS.HSF.TF.C.9

 $\cos\theta=\frac{4}{5}\ \ and\ \ \frac{3\pi}{2}<\theta<2\pi$  

Find the exact value of  $\tan2\theta$ .

•  $-1$  

•  $\frac{7}{24}$  

•  $\frac{24}{7}$  

•  $-\frac{24}{7}$  

Tags

CCSS.HSF.TF.C.9

Check all the forms of the Double-Angle Formula for cos 2x:

• cos²x - sin²x

• sin²x - cos²x

• 2cos²x - 1

• 1 - 2sin²x

Tags

CCSS.HSF.TF.C.9