Question

Help with this I don't know how to solve.

Answer 1

Answer:

The answer is $\sqrt{105}$ or approx. 10,25.

Step-by-step explanation:

$EG^2=DG*GF \\ EG^2 = ab \\ EG = \sqrt{5*16} \\ EG = \sqrt{80}$

Now let's find EF.

$EF^2 = GE^2+GF^2 \\ EF^2 = 80+256\\ EF=\sqrt{336}$

Now let's finally find DE.

$DE = \sqrt{DF^2-EF^2} \\ DE = \sqrt{21^2-336} \\ DE = \sqrt{441-336} \\ DE=\sqrt{105}$

$\sqrt{105} = 10,2469... = 10,25$