# Find the length of a diagonal of a 4 m × 12 m rectangle.

Solid Geometry

Find the length of a diagonal of a $$4 m \times 12 m$$ rectangle.

$$\displaystyle{d}^{{2}}={4}^{{2}}+{12}^{{2}}$$
$$\displaystyle{d}^{{2}}={16}+{144}$$
$$\displaystyle{d}^{{2}}={160}$$
$$\displaystyle{d}=\sqrt{{160}}$$
$$\displaystyle{d}={4}\sqrt{{10}}\sim{12.6}{m}$$