Can anyone help with this?

AD = 15

Step-by-step explanation:

Based on the Pythagoras Theorem, the longest side of a right-angled triangle is: where a and b are the legs of the triangle.

In triangle BDC, we can put in the formula to find BD.

85 =

85² = 77² + BD²

7225 = 5929 + BD²

BD² = 7225 - 5929

       = 1296

BD =

BD = 36

In triangle ABD, we can put in the formula to find AD.

39 =

39² = 36² + AD²

1521 = 1296 + AD²

AD² = 1521 - 1296

       = 225

AD =

AD = 15

6 hours 48 min

step-by-step explanation:

68÷5=13.6

13.6×30=408min=6 hours 48 min.

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we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4