You can put this solution on YOUR website! Prove that tan x (cot x + tan x) = sec^2x
LHS (Left hand side)
tan x (cot x + tan x)
=tan x * cot x + (tan x)(tan x)
=1+ tan^2 x
=1 + sin^2 x/cos ^ x
=(cos ^ 2 x + sin ^ x)/cos ^2 x
=1/cos^2 x
=sec ^2 x = RHS (right hand side)