Step-by-step explanation:
[tex]6.\\\\\dfrac{\tan x}{\cot x}\qquad\text{use}\ \cot x=\dfrac{1}{\tan x}\\\\=\dfrac{\tan x}{\frac{1}{\tan x}}=\tan x\cdot\dfrac{\tan x}{1}=\tan x\cdot\tan x=\left(\tan x\right)^2\qquad\text{use}\ \tan x=\dfrac{\sin x}{\cos x}\\\\=\left(\dfrac{\sin x}{\cos x}\right)^2\qquad\text{use}\ \left(\dfrac{a}{b}\right)^n=\dfrac{a^n}{b^n}\\\\=\dfrac{\sin^2x}{\cos^2x}\qquad\text{use}\ \sin^2x+\cos^2x=1\to\cos^2x=1-\sin^2x\\\\=\dfrac{\sin^2x}{1-\sin^2x}[/tex]
[tex]7.\\\\\cos x\cdot\cot x+\sin x\qquad\text{use}\ \cot x=\dfrac{\cos x}{\sin x}\\\\=\cos x\cdot\dfrac{\cos x}{\sin x}+\sin x=\dfrac{\cos^2x}{\sin x}+\dfrac{\sin^2x}{\sin x}=\dfrac{\cos^2x+\sin^2x}{\sin x}=\dfrac{1}{\sin x}[/tex]
