ANSWER
45.6cm to the nearest tenth.
EXPLANATION
The diagonal of the rectangular painting is 62cm.
The height of the painting is 42 cm.
The height of the painting h , the diagonal, and the width of the painting forms a right triangle with the diagonal being the hypotenuse.
From the Pythagoras Theorem,
[tex] {w}^{2} + {42}^{2} = {62}^{2}[/tex]
[tex] {w}^{2} = {62}^{2} - {42}^{2}[/tex]
[tex] {w}^{2} = 2080[/tex]
[tex] {w} = \sqrt{2080} [/tex]
[tex]w = 4 \sqrt{130} [/tex]
The width of the painting is 45.6cm to the nearest tenth.