The area of the rectangle = 4 * 2 = 8 (1)
And the area of triangle ABD is 1/2 of this = 4 (2)
O is the center of the rectangle = (2,1)
The slope of the line containing DB = 2/4 = 1/2
So....the slope of the line containing QP = -2
And this line passes through O, so the equation of this line is
y = -2 ( x -2) + 1
y = -2x + 4 + 1
y= -2x + 5
We can find the x coordinate of Q by letting y = 0
0 = -2x + 5
-5 = -2x
x = -5/-2 = 2.5
So the area of triangle DOQ = (1/2) DQ * height = (1/2) (2.5) (1) = 1.25 (3)
So....the area of the yellow region = (1) -(2) - (3) =
8 - 4 - 1.25 =
8 - 5.25 =
2.75
