Introduction to...

$${cos}^{2}0+{cos}^{2}10+{cos}^{2}20+{cos}^{2}30+{cos}^{2}40+{cos}^{2}50+{cos}^{2}60+{cos}^{2}70+{cos}^{2}80+{cos}^{2}90=$$

The value of $$\cos{\cfrac{\pi}{10}}\cos{\cfrac{2\pi}{10}}\cos{\cfrac{4\pi}{10}}\cos{\cfrac{8\pi}{10}}\cos{\cfrac{16\pi}{10}}$$ is:

Evaluate: $$\dfrac{{\sin}^{4}{\theta}-{\cos}^{4}{\theta}}{{\sin}^{2}{\theta}-{\cos}^{2}{\theta}}$$

If $$\sin \theta = \cos \theta$$, then $$\theta = ?$$

$$\sin { 2A } =2\sin { A } $$ is true then A = _____

$$\cot{1^0}\cot{2^0}\cot{3^0}\cot{4^0}...\cot{89^0}$$.

Choose the correct alternative:
$$\ cosec \theta = \dfrac { 1 } { \dots \ldots }$$

If $$\sin A+\cos A= {\sqrt2}$$ and $$\tan A+\cot A=2$$, then the value of $$\sec A\cdot \csc A$$ is equal to 

If $$\displaystyle  \tan \theta + \cot \theta = 2$$, then $$\displaystyle  \sin \theta = $$?

Consider the following statements : 
1. $$\cos\theta+\sec\theta$$ can never be equal to $$1.5$$
2. $$\tan\theta+\cot\theta$$ can never be less than to $$2$$
Which of the above statements is/are correct ?