[tex]\text{L.H.S}\\\\=\dfrac{\cos^2 t +4\cos t +4}{\cos t +2 }\\\\\\=\dfrac{(\cos t)^2 + 2\cdot 2\cos t+2^2}{\cos t +2}\\\\\\=\dfrac{(\cos t +2)^2 }{\cos t +2}\\\\\\=\cos t +2\\\\\\=\dfrac 1{\sec t} +2\\\\\\=\dfrac{2\sec t +1}{\sec t}\\\\\\=\text{R.H.S}\\\\\text{Proved.}[/tex]
