From the roof of a house the angle of depression of the top of a tree 20 ft. high was found to be 30°. If
the distance between the house and the tree is
10√2 find the height of the house.​

GB = CD = 20 ft, GC = BD = 10√3 ft, ∠FAC = 30°, AB = ? Or, AG = 10 ft. hence, the height of the house (AB) = 30 feet is the required answer.

$4034.40

the perimeter of the field is the sum of the lengths of the four sides:

47 yd + 158 yd + 47 yd + 158 yd = 410 yd

the cost of 3 ft (1 yd) of fence is 3×$3.28 = $9.84.

so the cost of jake's wood perimeter fance is

(410 yd) × ($9.84 /yd) = $4034.40