[tex]\text{R.H.S}\\\\=4\sin 45^{\circ} \cos 15^{\circ} \\\\=4\sin 45^{\circ} \cos (45^{\circ}-30^{\circ})\\ \\=4 \sin 45^{\circ} \left(\cos 45^{\circ} \cos 30^{\circ} +\sin 45^{\circ} \sin 30^{\circ} \right)\\\\=4 \left(\sin 45^{\circ} \cos 45^{\circ} \cos 30^{\circ} +\sin^2 45^{\circ} \sin 30^{\circ} \right)\\[/tex]
[tex]=4\left[\dfrac 1{\sqrt 2} \cdot \dfrac 1{\sqrt 2} \cdot \dfrac{\sqrt 3}2 +\left( \dfrac 1{\sqrt 2} \right)^2 \cdot \dfrac 12 \right]\\ \\=4\left(\dfrac{\sqrt 3}4 +\dfrac 14\right)\\\\=4\cdot \dfrac 14 \left(1+\sqrt 3\right)\\\\=1+\sqrt 3\\\\=\text{L.H.S}[/tex]
