Mathematics

Problem

\triangle DEF

\angle E = 90^{\circ}

. The altitude from

E

meets

DF

G

. If

DG = 12\,\text{cm}

and

DF = 20\,\text{cm}

, calculate the length of side

DE

. a)

16\,\text{cm}

3\sqrt{15}\,\text{cm}

4\sqrt{15}\,\text{cm}

4\sqrt{6}\,\text{cm}