$$1+\frac{1}{\cot^2\left(a\right)}=1\left(1-\frac{1}{\csc^2\left(a\right)}\right)$$

$$4x^2-28x+40$$

$$\frac{d}{dx}x+11$$

$$\frac{sec\left(x\right)}{cos\left(x\right)}-cot\left(x\right)$$

$$3b^4c-18b^3c^2+27b^2c^3$$

$$7x=-21$$

$$14^6$$