Orthonormal basis adapted to two vectors in $\mathbb{R}^2$

Consider the vectors \(\vec { a } _ { 1 }\) and \(\vec { a } _ { 2 }\) in \(\mathbb { R } ^ { 2 }\) with the lengths \(| \vec { a } _ { 1 } | = 2 , | \vec { a } _ { 2 } | = 6\) and the angle between them \(\phi = \frac { \pi } { 6 }\) . Construct the orthonormal basis \(\vec { e } _ { 1 } , \vec { e } _ { 2 }\) such that \(\vec { e } _ { 1 } | | \vec { a } _ { 1 }\) , and write the components of \(\vec { a } _ { 1 } , \vec { a } _ { 2 }\) in this basis.