In the figure below, GRAH is a rectangle, RA = 7, and GA = 10. Determine AH.

Because it is a rectangle we know that GR = HA and we can work out GR with pythagoras as rectangles always have right angeled corners

Pythagoras = a^2 + b^2 = c^2 

10^2= 100 7^2= 49

100-49 = 51

sqrt 51 you get 7.14