If ABCD is a square with side length a = 30, and b = 20, then what is the area of triangle CEF?
+128475 Let B =(0,0) let F = (30,20)
The slope ofthe segment BF = ( 20/30) = 2/3
So....the equation of a line through BF is y =(2/3) x
And when y = 30 then
30= (2/3)x
x= (3/2) 30 = 45
So DE = 45 - 30 = 15
And DF =10
So....the area of triangle DEC = (1/2)(DC)(DE) = (1/2) (30) (15) = 225
And the area of triangle DEF = (1/2) (DE) ( DF) = (1/2) (15)(10) = 75
So area of CEF = 225 - 75 = 150
