Dr Fiendish tells his p*g, Freddy, to mow the northeast side of the lawn(blue). However , Freddy accidentally mows the southwest side(yellow). What is the difference (in units squared) between the part Freddy has mowed and the part he should mow?
Assuming that the blue triangle is a right triangle:
-- using the Pythagorean Theorem, we get the missing side to be 5
-- the area will be: ½·5·12 = 30
The yellow triangle is a 30-60-90 triangle, so:
-- the side opposite the 30o angle is 13/2
-- the side adjacent to the 30o angle is (13/2)·sqrt(3)
-- the area will be: ½·( 13/2 )·[ (13/2)·sqrt(3) ] = (169/8)·sqrt(3)
The difference in area is: | 30 - (169/8)·sqrt(3) |