Basic Trigonometry

If $\sin\theta>0$ and  $\cos\theta<0$ ,  then  $\theta$  is in __________

• 1st quadrant

• 2nd quadrant

• 3rd quadrant

• 4th quadrant

 $\sin225\degree=$  __________

•  $\sin45\degree$  

•  $-\sin45\degree$  

•  $\sin25\degree$  

•  $-\sin25\degree$  

Given that $\cos\theta=\frac{3}{5}$  and  $270\degree\le\theta\le360\degree$ . What is value of  $\sin\theta$  ?

•  $-\frac{4}{5}$  

•  $\frac{4}{5}$  

•  $\frac{3}{4}$  

•  $-\frac{3}{4}$  

If $90\degree<\theta<180\degree$  , then  $\theta$  is called obtuse angle

• TRUE

• FALSE

If $\theta$ is in 3rd quadrant, then _________

•  $\sin\theta>0$  

•  $\tan\theta<0$  

•  $\cos\theta>0$  

•  $\sin\theta\times\cos\theta>0$  

Given that $\tan\alpha=\frac{1}{3}$ and  $180\degree\le\alpha\le270\degree$ . Which of the following is correct? [The answer are probably more than one]

•  $\sin\alpha=\frac{1}{\sqrt{10}}$  

•  $\cos\alpha=-\frac{3}{\sqrt{10}}$  

•  $\sin\alpha\times\cos\alpha=-\frac{3}{10}$  

•  $\frac{\sin\alpha}{\cos\alpha}=\frac{1}{3}$  

 $\sin200\degree$  is equivalent to __________

•  $\sin20\degree$  

•  $\sin70\degree$  

•  $-\sin20\degree$  

•  $-\sin70\degree$  

Which of the following is correct? [The answers are probably more than one]

• $\sin140\degree=\sin40\degree$

• $\cos310\degree=\cos50\degree$

• $\tan\left(-130\degree\right)=-\tan50\degree$

• $\sin\left(-100\degree\right)=-\sin80\degree$

If $\sin\theta>0$  and $\cos\theta<0$ , then __________

•  $\tan\theta>0$  

•  $\theta$  is obtuse

•  $\tan\theta<0$  

•  $\theta$  is acute

•  $90\degree<\theta<180\degree$  

Given that $\cos\alpha=-\frac{5}{13}$  and  $180\degree\le\alpha\le270\degree$ . What is value of  $\tan\alpha$  ? 

•  $\frac{5}{12}$  

•  $-\frac{5}{12}$  

•  $\frac{12}{5}$  

•  $-\frac{12}{5}$