Hello could someone explain how to answer these questions?

http://oi68.tinypic.com/nx6gl4.jpg

1st --- GH = BA = 6.8cm
DH = AE = 3.6cm
use Pythagorean Theorem to find DG (diagonal ~ hypotenuse, of the bottom rectangle)

AD = BC = 4.2 cm

tan AGD = opposite / adjacent = AD / DG = 4.2 / DG (from Pythag. theorem)
tan AGD = some decimal answer from above ...
Angle AGD = inverse tan (answer from above) <<< use a calculator.

2nd figure --- again parallel sides will be equal in length. --- use this, and pythag. theorem to find CF. Then use Pythag, theorem again to find BF

3rd figure --- AE = 1/2 of AC ... use Pythag. th. again to find AE
... sin AVE = opposite / hypotenuse = AE / AV
use inverse sine to find the angle