$\left(cscx-1\right)\left(cscx+1\right)=csc^2x-1$

$\left(8d^3-9d^2\:\right)\left(-d^2\:+2d\right)\:\left(-4d-7\right)$

$\tan x\cdot\cos x\cdot\cos ec\text{onte}x=1$

$\frac{6.5-4}{9-4}$

$10\left(-64-36\right)$

$6d=4\left(5d-2\right)+20$

$\frac{sin\left(4x\right)-sin\left(2x\right)}{cos\left(4x\right)+cos\left(2x\right)}=\tan\left(x\right)$